storaged: clean up disk stats code

Merged disk_stats_publisher into disk_stats_monitor class.

Moved proc file check to disk_stats class instead of doing so in
storaged, same for uid_io.

Added is_zero function to check zero disk_stats.

Added operators to compute disk_stats.

Change-Id: I277ae51f6fe18464f92e45c03471343784e67093
diff --git a/storaged/Android.bp b/storaged/Android.bp
index 25b433c..6aef8c8 100644
--- a/storaged/Android.bp
+++ b/storaged/Android.bp
@@ -44,6 +44,7 @@
 
     srcs: [
         "storaged.cpp",
+        "storaged_diskstats.cpp",
         "storaged_info.cpp",
         "storaged_service.cpp",
         "storaged_utils.cpp",
diff --git a/storaged/include/storaged.h b/storaged/include/storaged.h
index bd99361..28de7c9 100644
--- a/storaged/include/storaged.h
+++ b/storaged/include/storaged.h
@@ -29,23 +29,15 @@
 #include <batteryservice/IBatteryPropertiesListener.h>
 #include <batteryservice/IBatteryPropertiesRegistrar.h>
 
+#define FRIEND_TEST(test_case_name, test_name) \
+friend class test_case_name##_##test_name##_Test
+
+#include "storaged_diskstats.h"
 #include "storaged_info.h"
 #include "storaged_uid_monitor.h"
 
 using namespace android;
 
-#define FRIEND_TEST(test_case_name, test_name) \
-friend class test_case_name##_##test_name##_Test
-
-/* For debug */
-#ifdef DEBUG
-#define debuginfo(fmt, ...) \
- do {printf("%s():\t" fmt "\t[%s:%d]\n", __FUNCTION__, ##__VA_ARGS__, __FILE__, __LINE__);} \
- while(0)
-#else
-#define debuginfo(...)
-#endif
-
 #define ARRAY_SIZE(x)   (sizeof(x) / sizeof((x)[0]))
 
 #define SECTOR_SIZE ( 512 )
@@ -56,162 +48,6 @@
 #define HOUR_TO_SEC ( 3600 )
 #define DAY_TO_SEC ( 3600 * 24 )
 
-// number of attributes diskstats has
-#define DISK_STATS_SIZE ( 11 )
-// maximum size limit of a stats file
-#define DISK_STATS_FILE_MAX_SIZE ( 256 )
-#define DISK_STATS_IO_IN_FLIGHT_IDX ( 8 )
-struct disk_stats {
-    /* It will be extremely unlikely for any of the following entries to overflow.
-     * For read_bytes(which will be greater than any of the following entries), it
-     * will take 27 years to overflow uint64_t at the reading rate of 20GB/s, which
-     * is the peak memory transfer rate for current memory.
-     * The diskstats entries (first 11) need to be at top in this structure _after_
-     * compiler's optimization.
-     */
-    uint64_t read_ios;       // number of read I/Os processed
-    uint64_t read_merges;    // number of read I/Os merged with in-queue I/Os
-    uint64_t read_sectors;   // number of sectors read
-    uint64_t read_ticks;     // total wait time for read requests
-    uint64_t write_ios;      // number of write I/Os processed
-    uint64_t write_merges;   // number of write I/Os merged with in-queue I/Os
-    uint64_t write_sectors;  // number of sectors written
-    uint64_t write_ticks;    // total wait time for write requests
-    uint64_t io_in_flight;   // number of I/Os currently in flight
-    uint64_t io_ticks;       // total time this block device has been active
-    uint64_t io_in_queue;    // total wait time for all requests
-
-    uint64_t start_time;     // monotonic time accounting starts
-    uint64_t end_time;       // monotonic time accounting ends
-    uint32_t counter;        // private counter for accumulate calculations
-    double   io_avg;         // average io_in_flight for accumulate calculations
-};
-
-
-
-struct disk_perf {
-    uint32_t read_perf;         // read speed (kbytes/s)
-    uint32_t read_ios;          // read I/Os per second
-    uint32_t write_perf;        // write speed (kbytes/s)
-    uint32_t write_ios;         // write I/Os per second
-    uint32_t queue;             // I/Os in queue
-};
-
-class lock_t {
-    sem_t* mSem;
-public:
-    lock_t(sem_t* sem) {
-        mSem = sem;
-        sem_wait(mSem);
-    }
-    ~lock_t() {
-        sem_post(mSem);
-    }
-};
-
-class stream_stats {
-private:
-    double mSum;
-    double mSquareSum;
-    uint32_t mCnt;
-public:
-    stream_stats() : mSum(0), mSquareSum(0), mCnt(0) {};
-    ~stream_stats() {};
-    double get_mean() {
-        return mSum / mCnt;
-    }
-    double get_std() {
-        return sqrt(mSquareSum / mCnt - mSum * mSum / (mCnt * mCnt));
-    }
-    void add(uint32_t num) {
-        mSum += (double)num;
-        mSquareSum += (double)num * (double)num;
-        mCnt++;
-    }
-    void evict(uint32_t num) {
-        if (mSum < num || mSquareSum < (double)num * (double)num) return;
-        mSum -= (double)num;
-        mSquareSum -= (double)num * (double)num;
-        mCnt--;
-    }
-};
-
-#define MMC_DISK_STATS_PATH "/sys/block/mmcblk0/stat"
-#define SDA_DISK_STATS_PATH "/sys/block/sda/stat"
-#define EMMC_ECSD_PATH "/d/mmc0/mmc0:0001/ext_csd"
-#define UID_IO_STATS_PATH "/proc/uid_io/stats"
-
-class disk_stats_monitor {
-private:
-    FRIEND_TEST(storaged_test, disk_stats_monitor);
-    const char* DISK_STATS_PATH;
-    struct disk_stats mPrevious;
-    struct disk_stats mAccumulate;
-    bool mStall;
-    std::queue<struct disk_perf> mBuffer;
-    struct {
-        stream_stats read_perf;           // read speed (bytes/s)
-        stream_stats read_ios;            // read I/Os per second
-        stream_stats write_perf;          // write speed (bytes/s)
-        stream_stats write_ios;           // write I/O per second
-        stream_stats queue;               // I/Os in queue
-    } mStats;
-    bool mValid;
-    const uint32_t mWindow;
-    const double mSigma;
-    struct disk_perf mMean;
-    struct disk_perf mStd;
-
-    void update_mean();
-    void update_std();
-    void add(struct disk_perf* perf);
-    void evict(struct disk_perf* perf);
-    bool detect(struct disk_perf* perf);
-
-    void update(struct disk_stats* stats);
-
-public:
-    disk_stats_monitor(uint32_t window_size = 5, double sigma = 1.0) :
-            mStall(false),
-            mValid(false),
-            mWindow(window_size),
-            mSigma(sigma) {
-        memset(&mPrevious, 0, sizeof(mPrevious));
-        memset(&mMean, 0, sizeof(mMean));
-        memset(&mStd, 0, sizeof(mStd));
-
-        if (access(MMC_DISK_STATS_PATH, R_OK) >= 0) {
-            DISK_STATS_PATH = MMC_DISK_STATS_PATH;
-        } else {
-            DISK_STATS_PATH = SDA_DISK_STATS_PATH;
-        }
-    }
-    void update(void);
-};
-
-class disk_stats_publisher {
-private:
-    FRIEND_TEST(storaged_test, disk_stats_publisher);
-    const char* DISK_STATS_PATH;
-    struct disk_stats mAccumulate;
-    struct disk_stats mPrevious;
-public:
-    disk_stats_publisher(void) {
-        memset(&mAccumulate, 0, sizeof(struct disk_stats));
-        memset(&mPrevious, 0, sizeof(struct disk_stats));
-
-        if (access(MMC_DISK_STATS_PATH, R_OK) >= 0) {
-            DISK_STATS_PATH = MMC_DISK_STATS_PATH;
-        } else {
-            DISK_STATS_PATH = SDA_DISK_STATS_PATH;
-        }
-    }
-
-    ~disk_stats_publisher(void) {}
-    void publish(void);
-    void update(void);
-};
-
 // Periodic chores intervals in seconds
 #define DEFAULT_PERIODIC_CHORES_INTERVAL_UNIT ( 60 )
 #define DEFAULT_PERIODIC_CHORES_INTERVAL_DISK_STATS_PUBLISH ( 3600 )
@@ -225,8 +61,6 @@
     int periodic_chores_interval_unit;
     int periodic_chores_interval_disk_stats_publish;
     int periodic_chores_interval_uid_io;
-    bool proc_uid_io_available;      // whether uid_io is accessible
-    bool diskstats_available;   // whether diskstats is accessible
     int event_time_check_usec;  // check how much cputime spent in event loop
 };
 
@@ -235,7 +69,6 @@
 private:
     time_t mTimer;
     storaged_config mConfig;
-    disk_stats_publisher mDiskStats;
     disk_stats_monitor mDsm;
     uid_monitor mUidm;
     time_t mStarttime;
diff --git a/storaged/include/storaged_diskstats.h b/storaged/include/storaged_diskstats.h
new file mode 100644
index 0000000..ff030f6
--- /dev/null
+++ b/storaged/include/storaged_diskstats.h
@@ -0,0 +1,190 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _STORAGED_DISKSTATS_H_
+#define _STORAGED_DISKSTATS_H_
+
+#include <stdint.h>
+
+// number of attributes diskstats has
+#define DISK_STATS_SIZE ( 11 )
+
+#define MMC_DISK_STATS_PATH "/sys/block/mmcblk0/stat"
+#define SDA_DISK_STATS_PATH "/sys/block/sda/stat"
+
+struct disk_stats {
+    /* It will be extremely unlikely for any of the following entries to overflow.
+     * For read_bytes(which will be greater than any of the following entries), it
+     * will take 27 years to overflow uint64_t at the reading rate of 20GB/s, which
+     * is the peak memory transfer rate for current memory.
+     * The diskstats entries (first 11) need to be at top in this structure _after_
+     * compiler's optimization.
+     */
+    uint64_t read_ios;       // number of read I/Os processed
+    uint64_t read_merges;    // number of read I/Os merged with in-queue I/Os
+    uint64_t read_sectors;   // number of sectors read
+    uint64_t read_ticks;     // total wait time for read requests
+    uint64_t write_ios;      // number of write I/Os processed
+    uint64_t write_merges;   // number of write I/Os merged with in-queue I/Os
+    uint64_t write_sectors;  // number of sectors written
+    uint64_t write_ticks;    // total wait time for write requests
+    uint64_t io_in_flight;   // number of I/Os currently in flight
+    uint64_t io_ticks;       // total time this block device has been active
+    uint64_t io_in_queue;    // total wait time for all requests
+
+    uint64_t start_time;     // monotonic time accounting starts
+    uint64_t end_time;       // monotonic time accounting ends
+    uint32_t counter;        // private counter for accumulate calculations
+    double   io_avg;         // average io_in_flight for accumulate calculations
+
+    bool is_zero() {
+        return read_ios == 0 && write_ios == 0 &&
+               io_in_flight == 0 && io_ticks == 0 && io_in_queue == 0;
+    }
+
+    friend disk_stats operator- (disk_stats curr, const disk_stats& prev) {
+        curr.read_ios -= prev.read_ios;
+        curr.read_merges -= prev.read_merges;
+        curr.read_sectors -= prev.read_sectors;
+        curr.read_ticks -= prev.read_ticks;
+        curr.write_ios -= prev.write_ios;
+        curr.write_merges -= prev.write_merges;
+        curr.write_sectors -= prev.write_sectors;
+        curr.write_ticks -= prev.write_ticks;
+        /* skips io_in_flight, use current value */
+        curr.io_ticks -= prev.io_ticks;
+        curr.io_in_queue -= prev.io_in_queue;
+        return curr;
+    }
+
+    friend bool operator== (const disk_stats& a, const disk_stats& b) {
+        return a.read_ios == b.read_ios &&
+               a.read_merges == b.read_merges &&
+               a.read_sectors == b.read_sectors &&
+               a.read_ticks == b.read_ticks &&
+               a.write_ios == b.write_ios &&
+               a.write_merges == b.write_merges &&
+               a.write_sectors == b.write_sectors &&
+               a.write_ticks == b.write_ticks &&
+               /* skips io_in_flight */
+               a.io_ticks == b.io_ticks &&
+               a.io_in_queue == b.io_in_queue;
+    }
+
+    disk_stats& operator+= (const disk_stats& stats) {
+        read_ios += stats.read_ios;
+        read_merges += stats.read_merges;
+        read_sectors += stats.read_sectors;
+        read_ticks += stats.read_ticks;
+        write_ios += stats.write_ios;
+        write_merges += stats.write_merges;
+        write_sectors += stats.write_sectors;
+        write_ticks += stats.write_ticks;
+        /* skips io_in_flight, use current value */
+        io_ticks += stats.io_ticks;
+        io_in_queue += stats.io_in_queue;
+        return *this;
+    }
+};
+
+struct disk_perf {
+    uint32_t read_perf;         // read speed (kbytes/s)
+    uint32_t read_ios;          // read I/Os per second
+    uint32_t write_perf;        // write speed (kbytes/s)
+    uint32_t write_ios;         // write I/Os per second
+    uint32_t queue;             // I/Os in queue
+    bool is_zero() {
+        return read_perf == 0 && read_ios == 0 &&
+               write_perf == 0 && write_ios == 0 && queue == 0;
+    }
+};
+
+class stream_stats {
+private:
+    double mSum;
+    double mSquareSum;
+    uint32_t mCnt;
+public:
+    stream_stats() : mSum(0), mSquareSum(0), mCnt(0) {};
+    ~stream_stats() {};
+    double get_mean() {
+        return mSum / mCnt;
+    }
+    double get_std() {
+        return sqrt(mSquareSum / mCnt - mSum * mSum / (mCnt * mCnt));
+    }
+    void add(uint32_t num) {
+        mSum += (double)num;
+        mSquareSum += (double)num * (double)num;
+        mCnt++;
+    }
+    void evict(uint32_t num) {
+        if (mSum < num || mSquareSum < (double)num * (double)num) return;
+        mSum -= (double)num;
+        mSquareSum -= (double)num * (double)num;
+        mCnt--;
+    }
+};
+
+class disk_stats_monitor {
+private:
+    FRIEND_TEST(storaged_test, disk_stats_monitor);
+    const char* const DISK_STATS_PATH;
+    struct disk_stats mPrevious;
+    struct disk_stats mAccumulate;      /* reset after stall */
+    struct disk_stats mAccumulate_pub;  /* reset after publish */
+    bool mStall;
+    std::queue<struct disk_perf> mBuffer;
+    struct {
+        stream_stats read_perf;           // read speed (bytes/s)
+        stream_stats read_ios;            // read I/Os per second
+        stream_stats write_perf;          // write speed (bytes/s)
+        stream_stats write_ios;           // write I/O per second
+        stream_stats queue;               // I/Os in queue
+    } mStats;
+    bool mValid;
+    const uint32_t mWindow;
+    const double mSigma;
+    struct disk_perf mMean;
+    struct disk_perf mStd;
+
+    void update_mean();
+    void update_std();
+    void add(struct disk_perf* perf);
+    void evict(struct disk_perf* perf);
+    bool detect(struct disk_perf* perf);
+
+    void update(struct disk_stats* stats);
+
+public:
+    disk_stats_monitor(uint32_t window_size = 5, double sigma = 1.0) :
+        DISK_STATS_PATH(access(MMC_DISK_STATS_PATH, R_OK) ?
+                            (access(SDA_DISK_STATS_PATH, R_OK) ?
+                                nullptr :
+                                SDA_DISK_STATS_PATH) :
+                            MMC_DISK_STATS_PATH),
+        mPrevious(), mAccumulate(), mAccumulate_pub(),
+        mStall(false), mValid(false),
+        mWindow(window_size), mSigma(sigma),
+        mMean(), mStd() {}
+    bool enabled() {
+        return DISK_STATS_PATH != nullptr;
+    }
+    void update(void);
+    void publish(void);
+};
+
+#endif /* _STORAGED_DISKSTATS_H_ */
\ No newline at end of file
diff --git a/storaged/include/storaged_uid_monitor.h b/storaged/include/storaged_uid_monitor.h
index 86d3c28..c005c4c 100644
--- a/storaged/include/storaged_uid_monitor.h
+++ b/storaged/include/storaged_uid_monitor.h
@@ -85,6 +85,18 @@
     std::vector<struct uid_record> entries;
 };
 
+class lock_t {
+    sem_t* mSem;
+public:
+    lock_t(sem_t* sem) {
+        mSem = sem;
+        sem_wait(mSem);
+    }
+    ~lock_t() {
+        sem_post(mSem);
+    }
+};
+
 class uid_monitor {
 private:
     // last dump from /proc/uid_io/stats, uid -> uid_info
@@ -99,6 +111,8 @@
     sem_t um_lock;
     // start time for IO records
     uint64_t start_ts;
+    // true if UID_IO_STATS_PATH is accessible
+    const bool enable;
     // protobuf file for io_history
     static const std::string io_history_proto_file;
 
@@ -126,6 +140,7 @@
     // called by battery properties listener
     void set_charger_state(charger_stat_t stat);
     // called by storaged periodic_chore or dump with force_report
+    bool enabled() { return enable; };
     void report();
 };
 
diff --git a/storaged/include/storaged_utils.h b/storaged/include/storaged_utils.h
index 1435707..06ab955 100644
--- a/storaged/include/storaged_utils.h
+++ b/storaged/include/storaged_utils.h
@@ -27,9 +27,8 @@
 // Diskstats
 bool parse_disk_stats(const char* disk_stats_path, struct disk_stats* stats);
 struct disk_perf get_disk_perf(struct disk_stats* stats);
-struct disk_stats get_inc_disk_stats(struct disk_stats* prev, struct disk_stats* curr);
+void get_inc_disk_stats(const struct disk_stats* prev, const struct disk_stats* curr, struct disk_stats* inc);
 void add_disk_stats(struct disk_stats* src, struct disk_stats* dst);
-bool parse_emmc_ecsd(int ext_csd_fd, struct emmc_info* info);
 
 // UID I/O
 void sort_running_uids_info(std::vector<struct uid_info> &uids);
@@ -37,8 +36,4 @@
 // Logging
 void log_console_running_uids_info(const std::vector<struct uid_info>& uids, bool flag_dump_task);
 
-void log_debug_disk_perf(struct disk_perf* perf, const char* type);
-
-void log_event_disk_stats(struct disk_stats* stats, const char* type);
-void log_event_emmc_info(struct emmc_info* info_);
 #endif /* _STORAGED_UTILS_H_ */
diff --git a/storaged/main.cpp b/storaged/main.cpp
index 49bd916..efab692 100644
--- a/storaged/main.cpp
+++ b/storaged/main.cpp
@@ -60,7 +60,7 @@
     return NULL;
 }
 
-static void help_message(void) {
+void help_message(void) {
     printf("usage: storaged [OPTION]\n");
     printf("  -u    --uid                   Dump uid I/O usage to stdout\n");
     printf("  -t    --task                  Dump task I/O usage to stdout\n");
diff --git a/storaged/storaged.cpp b/storaged/storaged.cpp
index 49592eb..0cf80a4 100644
--- a/storaged/storaged.cpp
+++ b/storaged/storaged.cpp
@@ -31,124 +31,8 @@
 #include <storaged.h>
 #include <storaged_utils.h>
 
-/* disk_stats_publisher */
-void disk_stats_publisher::publish(void) {
-    // Logging
-    struct disk_perf perf = get_disk_perf(&mAccumulate);
-    log_debug_disk_perf(&perf, "regular");
-    log_event_disk_stats(&mAccumulate, "regular");
-    // Reset global structures
-    memset(&mAccumulate, 0, sizeof(struct disk_stats));
-}
 
-void disk_stats_publisher::update(void) {
-    struct disk_stats curr;
-    if (parse_disk_stats(DISK_STATS_PATH, &curr)) {
-        struct disk_stats inc = get_inc_disk_stats(&mPrevious, &curr);
-        add_disk_stats(&inc, &mAccumulate);
-#ifdef DEBUG
-//            log_kernel_disk_stats(&mPrevious, "prev stats");
-//            log_kernel_disk_stats(&curr, "curr stats");
-//            log_kernel_disk_stats(&inc, "inc stats");
-//            log_kernel_disk_stats(&mAccumulate, "accumulated stats");
-#endif
-        mPrevious = curr;
-    }
-}
-
-/* disk_stats_monitor */
-void disk_stats_monitor::update_mean() {
-    CHECK(mValid);
-    mMean.read_perf = (uint32_t)mStats.read_perf.get_mean();
-    mMean.read_ios = (uint32_t)mStats.read_ios.get_mean();
-    mMean.write_perf = (uint32_t)mStats.write_perf.get_mean();
-    mMean.write_ios = (uint32_t)mStats.write_ios.get_mean();
-    mMean.queue = (uint32_t)mStats.queue.get_mean();
-}
-
-void disk_stats_monitor::update_std() {
-    CHECK(mValid);
-    mStd.read_perf = (uint32_t)mStats.read_perf.get_std();
-    mStd.read_ios = (uint32_t)mStats.read_ios.get_std();
-    mStd.write_perf = (uint32_t)mStats.write_perf.get_std();
-    mStd.write_ios = (uint32_t)mStats.write_ios.get_std();
-    mStd.queue = (uint32_t)mStats.queue.get_std();
-}
-
-void disk_stats_monitor::add(struct disk_perf* perf) {
-    mStats.read_perf.add(perf->read_perf);
-    mStats.read_ios.add(perf->read_ios);
-    mStats.write_perf.add(perf->write_perf);
-    mStats.write_ios.add(perf->write_ios);
-    mStats.queue.add(perf->queue);
-}
-
-void disk_stats_monitor::evict(struct disk_perf* perf) {
-    mStats.read_perf.evict(perf->read_perf);
-    mStats.read_ios.evict(perf->read_ios);
-    mStats.write_perf.evict(perf->write_perf);
-    mStats.write_ios.evict(perf->write_ios);
-    mStats.queue.evict(perf->queue);
-}
-
-bool disk_stats_monitor::detect(struct disk_perf* perf) {
-    return ((double)perf->queue >= (double)mMean.queue + mSigma * (double)mStd.queue) &&
-            ((double)perf->read_perf < (double)mMean.read_perf - mSigma * (double)mStd.read_perf) &&
-            ((double)perf->write_perf < (double)mMean.write_perf - mSigma * (double)mStd.write_perf);
-}
-
-void disk_stats_monitor::update(struct disk_stats* stats) {
-    struct disk_stats inc = get_inc_disk_stats(&mPrevious, stats);
-    struct disk_perf perf = get_disk_perf(&inc);
-    // Update internal data structures
-    if (LIKELY(mValid)) {
-        CHECK_EQ(mBuffer.size(), mWindow);
-
-        if (UNLIKELY(detect(&perf))) {
-            mStall = true;
-            add_disk_stats(&inc, &mAccumulate);
-            log_debug_disk_perf(&mMean, "stalled_mean");
-            log_debug_disk_perf(&mStd, "stalled_std");
-        } else {
-            if (mStall) {
-                struct disk_perf acc_perf = get_disk_perf(&mAccumulate);
-                log_debug_disk_perf(&acc_perf, "stalled");
-                log_event_disk_stats(&mAccumulate, "stalled");
-                mStall = false;
-                memset(&mAccumulate, 0, sizeof(mAccumulate));
-            }
-        }
-
-        evict(&mBuffer.front());
-        mBuffer.pop();
-        add(&perf);
-        mBuffer.push(perf);
-
-        update_mean();
-        update_std();
-
-    } else { /* mValid == false */
-        CHECK_LT(mBuffer.size(), mWindow);
-        add(&perf);
-        mBuffer.push(perf);
-        if (mBuffer.size() == mWindow) {
-            mValid = true;
-            update_mean();
-            update_std();
-        }
-    }
-
-    mPrevious = *stats;
-}
-
-void disk_stats_monitor::update(void) {
-    struct disk_stats curr;
-    if (LIKELY(parse_disk_stats(DISK_STATS_PATH, &curr))) {
-        update(&curr);
-    }
-}
-
-static sp<IBatteryPropertiesRegistrar> get_battery_properties_service() {
+sp<IBatteryPropertiesRegistrar> get_battery_properties_service() {
     sp<IServiceManager> sm = defaultServiceManager();
     if (sm == NULL) return NULL;
 
@@ -161,7 +45,7 @@
     return battery_properties;
 }
 
-static inline charger_stat_t is_charger_on(int64_t prop) {
+inline charger_stat_t is_charger_on(int64_t prop) {
     return (prop == BATTERY_STATUS_CHARGING || prop == BATTERY_STATUS_FULL) ?
         CHARGER_ON : CHARGER_OFF;
 }
@@ -171,7 +55,7 @@
 }
 
 void storaged_t::init_battery_service() {
-    if (!mConfig.proc_uid_io_available)
+    if (!mUidm.enabled())
         return;
 
     battery_properties = get_battery_properties_service();
@@ -206,43 +90,39 @@
 
 /* storaged_t */
 storaged_t::storaged_t(void) {
-    if (access(MMC_DISK_STATS_PATH, R_OK) < 0 && access(SDA_DISK_STATS_PATH, R_OK) < 0) {
-        mConfig.diskstats_available = false;
-    } else {
-        mConfig.diskstats_available = true;
-    }
-
-    mConfig.proc_uid_io_available = (access(UID_IO_STATS_PATH, R_OK) == 0);
-
     mConfig.periodic_chores_interval_unit =
-        property_get_int32("ro.storaged.event.interval", DEFAULT_PERIODIC_CHORES_INTERVAL_UNIT);
+        property_get_int32("ro.storaged.event.interval",
+                           DEFAULT_PERIODIC_CHORES_INTERVAL_UNIT);
 
     mConfig.event_time_check_usec =
         property_get_int32("ro.storaged.event.perf_check", 0);
 
     mConfig.periodic_chores_interval_disk_stats_publish =
-        property_get_int32("ro.storaged.disk_stats_pub", DEFAULT_PERIODIC_CHORES_INTERVAL_DISK_STATS_PUBLISH);
+        property_get_int32("ro.storaged.disk_stats_pub",
+                           DEFAULT_PERIODIC_CHORES_INTERVAL_DISK_STATS_PUBLISH);
 
     mConfig.periodic_chores_interval_uid_io =
-        property_get_int32("ro.storaged.uid_io.interval", DEFAULT_PERIODIC_CHORES_INTERVAL_UID_IO);
+        property_get_int32("ro.storaged.uid_io.interval",
+                           DEFAULT_PERIODIC_CHORES_INTERVAL_UID_IO);
 
     storage_info.reset(storage_info_t::get_storage_info());
 
     mStarttime = time(NULL);
+    mTimer = 0;
 }
 
 void storaged_t::event(void) {
-    if (mConfig.diskstats_available) {
-        mDiskStats.update();
+    storage_info->refresh();
+
+    if (mDsm.enabled()) {
         mDsm.update();
-        storage_info->refresh();
-        if (mTimer && (mTimer % mConfig.periodic_chores_interval_disk_stats_publish) == 0) {
-            mDiskStats.publish();
+        if (!(mTimer % mConfig.periodic_chores_interval_disk_stats_publish)) {
+            mDsm.publish();
         }
     }
 
-    if (mConfig.proc_uid_io_available && mTimer &&
-            (mTimer % mConfig.periodic_chores_interval_uid_io) == 0) {
+    if (mUidm.enabled() &&
+        !(mTimer % mConfig.periodic_chores_interval_uid_io)) {
         mUidm.report();
     }
 
diff --git a/storaged/storaged_diskstats.cpp b/storaged/storaged_diskstats.cpp
new file mode 100644
index 0000000..0604e0a
--- /dev/null
+++ b/storaged/storaged_diskstats.cpp
@@ -0,0 +1,260 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "storaged"
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#include <sstream>
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <log/log_event_list.h>
+
+#include "storaged.h"
+#include "storaged_diskstats.h"
+
+namespace {
+
+#ifdef DEBUG
+void log_debug_disk_perf(struct disk_perf* perf, const char* type) {
+    // skip if the input structure are all zeros
+    if (perf == NULL || perf->is_zero()) return;
+
+    LOG_TO(SYSTEM, INFO) << "disk_perf " << type
+              << " rd: " << perf->read_perf << " kbps, " << perf->read_ios << " iops"
+              << " wr: " << perf->write_perf << " kbps, " << perf->write_ios << " iops"
+              << " q: " << perf->queue;
+}
+#else
+void log_debug_disk_perf(struct disk_perf* perf, const char* type) {}
+#endif
+
+void log_event_disk_stats(struct disk_stats* stats, const char* type) {
+    // skip if the input structure are all zeros
+    if (stats == NULL || stats->is_zero()) return;
+
+    android_log_event_list(EVENTLOGTAG_DISKSTATS)
+        << type << stats->start_time << stats->end_time
+        << stats->read_ios << stats->read_merges
+        << stats->read_sectors << stats->read_ticks
+        << stats->write_ios << stats->write_merges
+        << stats->write_sectors << stats->write_ticks
+        << (uint64_t)stats->io_avg << stats->io_ticks << stats->io_in_queue
+        << LOG_ID_EVENTS;
+}
+
+} // namespace
+
+bool parse_disk_stats(const char* disk_stats_path, struct disk_stats* stats)
+{
+    // Get time
+    struct timespec ts;
+    // Use monotonic to exclude suspend time so that we measure IO bytes/sec
+    // when system is running.
+    int ret = clock_gettime(CLOCK_MONOTONIC, &ts);
+    if (ret < 0) {
+        PLOG_TO(SYSTEM, ERROR) << "clock_gettime() failed";
+        return false;
+    }
+
+    std::string buffer;
+    if (!android::base::ReadFileToString(disk_stats_path, &buffer)) {
+        PLOG_TO(SYSTEM, ERROR) << disk_stats_path << ": ReadFileToString failed.";
+        return false;
+    }
+
+    // Regular diskstats entries
+    std::stringstream ss(buffer);
+    for (uint i = 0; i < DISK_STATS_SIZE; ++i) {
+        ss >> *((uint64_t*)stats + i);
+    }
+    // Other entries
+    stats->start_time = 0;
+    stats->end_time = (uint64_t)ts.tv_sec * SEC_TO_MSEC +
+        ts.tv_nsec / (MSEC_TO_USEC * USEC_TO_NSEC);
+    stats->counter = 1;
+    stats->io_avg = (double)stats->io_in_flight;
+    return true;
+}
+
+struct disk_perf get_disk_perf(struct disk_stats* stats)
+{
+    struct disk_perf perf = {};
+
+    if (stats->io_ticks) {
+        if (stats->read_ticks) {
+            unsigned long long divisor = stats->read_ticks * stats->io_ticks;
+            perf.read_perf = ((unsigned long long)SECTOR_SIZE *
+                              stats->read_sectors * stats->io_in_queue +
+                              (divisor >> 1)) / divisor;
+            perf.read_ios = ((unsigned long long)SEC_TO_MSEC *
+                             stats->read_ios * stats->io_in_queue +
+                             (divisor >> 1)) / divisor;
+        }
+        if (stats->write_ticks) {
+            unsigned long long divisor = stats->write_ticks * stats->io_ticks;
+            perf.write_perf = ((unsigned long long)SECTOR_SIZE *
+                               stats->write_sectors * stats->io_in_queue +
+                               (divisor >> 1)) / divisor;
+            perf.write_ios = ((unsigned long long)SEC_TO_MSEC *
+                              stats->write_ios * stats->io_in_queue +
+                              (divisor >> 1)) / divisor;
+        }
+        perf.queue = (stats->io_in_queue + (stats->io_ticks >> 1)) /
+                     stats->io_ticks;
+    }
+    return perf;
+}
+
+void get_inc_disk_stats(const struct disk_stats* prev, const struct disk_stats* curr,
+                        struct disk_stats* inc)
+{
+    *inc = *curr - *prev;
+    inc->start_time = prev->end_time;
+    inc->end_time = curr->end_time;
+    inc->io_avg = curr->io_avg;
+    inc->counter = 1;
+}
+
+// Add src to dst
+void add_disk_stats(struct disk_stats* src, struct disk_stats* dst)
+{
+    if (dst->end_time != 0 && dst->end_time != src->start_time) {
+        LOG_TO(SYSTEM, WARNING) << "Two dis-continuous periods of diskstats"
+            << " are added. dst end with " << dst->end_time
+            << ", src start with " << src->start_time;
+    }
+
+    *dst += *src;
+
+    dst->io_in_flight = src->io_in_flight;
+    if (dst->counter + src->counter) {
+        dst->io_avg =
+            ((dst->io_avg * dst->counter) + (src->io_avg * src->counter)) /
+            (dst->counter + src->counter);
+    }
+    dst->counter += src->counter;
+    dst->end_time = src->end_time;
+    if (dst->start_time == 0) {
+        dst->start_time = src->start_time;
+    }
+}
+
+/* disk_stats_monitor */
+void disk_stats_monitor::update_mean()
+{
+    CHECK(mValid);
+    mMean.read_perf = (uint32_t)mStats.read_perf.get_mean();
+    mMean.read_ios = (uint32_t)mStats.read_ios.get_mean();
+    mMean.write_perf = (uint32_t)mStats.write_perf.get_mean();
+    mMean.write_ios = (uint32_t)mStats.write_ios.get_mean();
+    mMean.queue = (uint32_t)mStats.queue.get_mean();
+}
+
+void disk_stats_monitor::update_std()
+{
+    CHECK(mValid);
+    mStd.read_perf = (uint32_t)mStats.read_perf.get_std();
+    mStd.read_ios = (uint32_t)mStats.read_ios.get_std();
+    mStd.write_perf = (uint32_t)mStats.write_perf.get_std();
+    mStd.write_ios = (uint32_t)mStats.write_ios.get_std();
+    mStd.queue = (uint32_t)mStats.queue.get_std();
+}
+
+void disk_stats_monitor::add(struct disk_perf* perf)
+{
+    mStats.read_perf.add(perf->read_perf);
+    mStats.read_ios.add(perf->read_ios);
+    mStats.write_perf.add(perf->write_perf);
+    mStats.write_ios.add(perf->write_ios);
+    mStats.queue.add(perf->queue);
+}
+
+void disk_stats_monitor::evict(struct disk_perf* perf) {
+    mStats.read_perf.evict(perf->read_perf);
+    mStats.read_ios.evict(perf->read_ios);
+    mStats.write_perf.evict(perf->write_perf);
+    mStats.write_ios.evict(perf->write_ios);
+    mStats.queue.evict(perf->queue);
+}
+
+bool disk_stats_monitor::detect(struct disk_perf* perf)
+{
+    return ((double)perf->queue >= (double)mMean.queue + mSigma * (double)mStd.queue) &&
+        ((double)perf->read_perf < (double)mMean.read_perf - mSigma * (double)mStd.read_perf) &&
+        ((double)perf->write_perf < (double)mMean.write_perf - mSigma * (double)mStd.write_perf);
+}
+
+void disk_stats_monitor::update(struct disk_stats* curr)
+{
+    disk_stats inc;
+    get_inc_disk_stats(&mPrevious, curr, &inc);
+    add_disk_stats(&inc, &mAccumulate_pub);
+
+    struct disk_perf perf = get_disk_perf(&inc);
+    log_debug_disk_perf(&perf, "regular");
+
+    add(&perf);
+    mBuffer.push(perf);
+    if (mBuffer.size() > mWindow) {
+        evict(&mBuffer.front());
+        mBuffer.pop();
+        mValid = true;
+    }
+
+    // Update internal data structures
+    if (LIKELY(mValid)) {
+        CHECK_EQ(mBuffer.size(), mWindow);
+        update_mean();
+        update_std();
+        if (UNLIKELY(detect(&perf))) {
+            mStall = true;
+            add_disk_stats(&inc, &mAccumulate);
+            log_debug_disk_perf(&mMean, "stalled_mean");
+            log_debug_disk_perf(&mStd, "stalled_std");
+        } else {
+            if (mStall) {
+                struct disk_perf acc_perf = get_disk_perf(&mAccumulate);
+                log_debug_disk_perf(&acc_perf, "stalled");
+                log_event_disk_stats(&mAccumulate, "stalled");
+                mStall = false;
+                memset(&mAccumulate, 0, sizeof(mAccumulate));
+            }
+        }
+    }
+
+    mPrevious = *curr;
+}
+
+void disk_stats_monitor::update() {
+    disk_stats curr;
+    if (!parse_disk_stats(DISK_STATS_PATH, &curr)) {
+        return;
+    }
+
+    update(&curr);
+}
+
+void disk_stats_monitor::publish(void)
+{
+    struct disk_perf perf = get_disk_perf(&mAccumulate_pub);
+    log_debug_disk_perf(&perf, "regular");
+    log_event_disk_stats(&mAccumulate, "regular");
+    // Reset global structures
+    memset(&mAccumulate_pub, 0, sizeof(struct disk_stats));
+}
diff --git a/storaged/storaged_info.cpp b/storaged/storaged_info.cpp
index b5fb13e..fc2351f 100644
--- a/storaged/storaged_info.cpp
+++ b/storaged/storaged_info.cpp
@@ -39,12 +39,16 @@
 
 const string ufs_info_t::health_file = "/sys/devices/soc/624000.ufshc/health";
 
-static bool FileExists(const std::string& filename)
+namespace {
+
+bool FileExists(const std::string& filename)
 {
   struct stat buffer;
   return stat(filename.c_str(), &buffer) == 0;
 }
 
+} // namespace
+
 storage_info_t* storage_info_t::get_storage_info()
 {
     if (FileExists(emmc_info_t::emmc_sysfs) ||
@@ -121,6 +125,8 @@
     return true;
 }
 
+namespace {
+
 const size_t EXT_CSD_FILE_MIN_SIZE = 1024;
 /* 2 characters in string for each byte */
 const size_t EXT_CSD_REV_IDX = 192 * 2;
@@ -128,6 +134,8 @@
 const size_t EXT_DEVICE_LIFE_TIME_EST_A_IDX = 268 * 2;
 const size_t EXT_DEVICE_LIFE_TIME_EST_B_IDX = 269 * 2;
 
+} // namespace
+
 bool emmc_info_t::report_debugfs()
 {
     string buffer;
diff --git a/storaged/storaged_uid_monitor.cpp b/storaged/storaged_uid_monitor.cpp
index a69bc33..66a9e35 100644
--- a/storaged/storaged_uid_monitor.cpp
+++ b/storaged/storaged_uid_monitor.cpp
@@ -45,11 +45,16 @@
 using namespace google::protobuf::io;
 using namespace storaged_proto;
 
-static bool refresh_uid_names;
-static const uint32_t crc_init = 0x5108A4ED; /* STORAGED */
+namespace {
+
+bool refresh_uid_names;
+const uint32_t crc_init = 0x5108A4ED; /* STORAGED */
+const char* UID_IO_STATS_PATH = "/proc/uid_io/stats";
+
+} // namepsace
 
 const std::string uid_monitor::io_history_proto_file =
-    "/data/misc/storaged/io_history.proto";
+"/data/misc/storaged/io_history.proto";
 
 std::unordered_map<uint32_t, struct uid_info> uid_monitor::get_uid_io_stats()
 {
@@ -119,7 +124,9 @@
     return true;
 }
 
-static void get_uid_names(const vector<int>& uids, const vector<std::string*>& uid_names)
+namespace {
+
+void get_uid_names(const vector<int>& uids, const vector<std::string*>& uid_names)
 {
     sp<IServiceManager> sm = defaultServiceManager();
     if (sm == NULL) {
@@ -151,6 +158,8 @@
     refresh_uid_names = false;
 }
 
+} // namespace
+
 std::unordered_map<uint32_t, struct uid_info> uid_monitor::get_uid_io_stats_locked()
 {
     std::unordered_map<uint32_t, struct uid_info> uid_io_stats;
@@ -197,9 +206,11 @@
     return uid_io_stats;
 }
 
-static const int MAX_UID_RECORDS_SIZE = 1000 * 48; // 1000 uids in 48 hours
+namespace {
 
-static inline size_t history_size(
+const int MAX_UID_RECORDS_SIZE = 1000 * 48; // 1000 uids in 48 hours
+
+inline size_t history_size(
     const std::map<uint64_t, struct uid_records>& history)
 {
     size_t count = 0;
@@ -209,6 +220,8 @@
     return count;
 }
 
+} // namespace
+
 void uid_monitor::add_records_locked(uint64_t curr_ts)
 {
     // remove records more than 5 days old
@@ -367,7 +380,9 @@
     flush_io_history_to_proto();
 }
 
-static void set_io_usage_proto(IOUsage* usage_proto, const struct io_usage& usage)
+namespace {
+
+void set_io_usage_proto(IOUsage* usage_proto, const struct io_usage& usage)
 {
     usage_proto->set_rd_fg_chg_on(usage.bytes[READ][FOREGROUND][CHARGER_ON]);
     usage_proto->set_rd_fg_chg_off(usage.bytes[READ][FOREGROUND][CHARGER_OFF]);
@@ -379,7 +394,7 @@
     usage_proto->set_wr_bg_chg_off(usage.bytes[WRITE][BACKGROUND][CHARGER_OFF]);
 }
 
-static void get_io_usage_proto(struct io_usage* usage, const IOUsage& io_proto)
+void get_io_usage_proto(struct io_usage* usage, const IOUsage& io_proto)
 {
     usage->bytes[READ][FOREGROUND][CHARGER_ON] = io_proto.rd_fg_chg_on();
     usage->bytes[READ][FOREGROUND][CHARGER_OFF] = io_proto.rd_fg_chg_off();
@@ -391,6 +406,8 @@
     usage->bytes[WRITE][BACKGROUND][CHARGER_OFF] = io_proto.wr_bg_chg_off();
 }
 
+} // namespace
+
 void uid_monitor::flush_io_history_to_proto()
 {
     UidIOHistoryProto out_proto;
@@ -510,6 +527,7 @@
 }
 
 uid_monitor::uid_monitor()
+    : enable(!access(UID_IO_STATS_PATH, R_OK))
 {
     sem_init(&um_lock, 0, 1);
 }
diff --git a/storaged/storaged_utils.cpp b/storaged/storaged_utils.cpp
index 59cf251..533bf78 100644
--- a/storaged/storaged_utils.cpp
+++ b/storaged/storaged_utils.cpp
@@ -42,124 +42,7 @@
 #include <storaged.h>
 #include <storaged_utils.h>
 
-bool parse_disk_stats(const char* disk_stats_path, struct disk_stats* stats) {
-    // Get time
-    struct timespec ts;
-    // Use monotonic to exclude suspend time so that we measure IO bytes/sec
-    // when system is running.
-    int ret = clock_gettime(CLOCK_MONOTONIC, &ts);
-    if (ret < 0) {
-        PLOG_TO(SYSTEM, ERROR) << "clock_gettime() failed";
-        return false;
-    }
-
-    std::string buffer;
-    if (!android::base::ReadFileToString(disk_stats_path, &buffer)) {
-        PLOG_TO(SYSTEM, ERROR) << disk_stats_path << ": ReadFileToString failed.";
-        return false;
-    }
-
-    // Regular diskstats entries
-    std::stringstream ss(buffer);
-    for (uint i = 0; i < DISK_STATS_SIZE; ++i) {
-        ss >> *((uint64_t*)stats + i);
-    }
-    // Other entries
-    stats->start_time = 0;
-    stats->end_time = (uint64_t)ts.tv_sec * SEC_TO_MSEC +
-        ts.tv_nsec / (MSEC_TO_USEC * USEC_TO_NSEC);
-    stats->counter = 1;
-    stats->io_avg = (double)stats->io_in_flight;
-    return true;
-}
-
-struct disk_perf get_disk_perf(struct disk_stats* stats) {
-    struct disk_perf perf;
-    memset(&perf, 0, sizeof(struct disk_perf));  // initialize
-
-    if (stats->io_ticks) {
-        if (stats->read_ticks) {
-            unsigned long long divisor = stats->read_ticks * stats->io_ticks;
-            perf.read_perf = ((unsigned long long)SECTOR_SIZE *
-                                        stats->read_sectors *
-                                        stats->io_in_queue +
-                                        (divisor >> 1)) /
-                                            divisor;
-            perf.read_ios = ((unsigned long long)SEC_TO_MSEC *
-                                        stats->read_ios *
-                                        stats->io_in_queue +
-                                        (divisor >> 1)) /
-                                            divisor;
-        }
-        if (stats->write_ticks) {
-            unsigned long long divisor = stats->write_ticks * stats->io_ticks;
-                        perf.write_perf = ((unsigned long long)SECTOR_SIZE *
-                                                    stats->write_sectors *
-                                                    stats->io_in_queue +
-                                                    (divisor >> 1)) /
-                                                        divisor;
-                        perf.write_ios = ((unsigned long long)SEC_TO_MSEC *
-                                                    stats->write_ios *
-                                                    stats->io_in_queue +
-                                                    (divisor >> 1)) /
-                                                        divisor;
-        }
-        perf.queue = (stats->io_in_queue + (stats->io_ticks >> 1)) /
-                                stats->io_ticks;
-    }
-    return perf;
-}
-
-struct disk_stats get_inc_disk_stats(struct disk_stats* prev, struct disk_stats* curr) {
-    struct disk_stats inc;
-    for (uint i = 0; i < DISK_STATS_SIZE; ++i) {
-        if (i == DISK_STATS_IO_IN_FLIGHT_IDX) {
-            continue;
-        }
-
-        *((uint64_t*)&inc + i) =
-                *((uint64_t*)curr + i) - *((uint64_t*)prev + i);
-    }
-    // io_in_flight is exception
-    inc.io_in_flight = curr->io_in_flight;
-
-    inc.start_time = prev->end_time;
-    inc.end_time = curr->end_time;
-    inc.io_avg = curr->io_avg;
-    inc.counter = 1;
-
-    return inc;
-}
-
-// Add src to dst
-void add_disk_stats(struct disk_stats* src, struct disk_stats* dst) {
-    if (dst->end_time != 0 && dst->end_time != src->start_time) {
-        LOG_TO(SYSTEM, WARNING) << "Two dis-continuous periods of diskstats"
-            << " are added. dst end with " << dst->end_time
-            << ", src start with " << src->start_time;
-    }
-
-    for (uint i = 0; i < DISK_STATS_SIZE; ++i) {
-        if (i == DISK_STATS_IO_IN_FLIGHT_IDX) {
-            continue;
-        }
-
-        *((uint64_t*)dst + i) += *((uint64_t*)src + i);
-    }
-
-    dst->io_in_flight = src->io_in_flight;
-    if (dst->counter + src->counter) {
-        dst->io_avg = ((dst->io_avg * dst->counter) + (src->io_avg * src->counter)) /
-                        (dst->counter + src->counter);
-    }
-    dst->counter += src->counter;
-    dst->end_time = src->end_time;
-    if (dst->start_time == 0) {
-        dst->start_time = src->start_time;
-    }
-}
-
-static bool cmp_uid_info(struct uid_info l, struct uid_info r) {
+bool cmp_uid_info(struct uid_info l, struct uid_info r) {
     // Compare background I/O first.
     for (int i = UID_STATS - 1; i >= 0; i--) {
         uint64_t l_bytes = l.io[i].read_bytes + l.io[i].write_bytes;
@@ -208,39 +91,3 @@
     }
     fflush(stdout);
 }
-
-#if DEBUG
-void log_debug_disk_perf(struct disk_perf* perf, const char* type) {
-    // skip if the input structure are all zeros
-    if (perf == NULL) return;
-    struct disk_perf zero_cmp;
-    memset(&zero_cmp, 0, sizeof(zero_cmp));
-    if (memcmp(&zero_cmp, perf, sizeof(struct disk_perf)) == 0) return;
-
-    LOG_TO(SYSTEM, INFO) << "perf(ios) " << type
-              << " rd:" << perf->read_perf << "KB/s(" << perf->read_ios << "/s)"
-              << " wr:" << perf->write_perf << "KB/s(" << perf->write_ios << "/s)"
-              << " q:" << perf->queue;
-}
-#else
-void log_debug_disk_perf(struct disk_perf* /* perf */, const char* /* type */) {}
-#endif
-
-void log_event_disk_stats(struct disk_stats* stats, const char* type) {
-    // skip if the input structure are all zeros
-    if (stats == NULL) return;
-    struct disk_stats zero_cmp;
-    memset(&zero_cmp, 0, sizeof(zero_cmp));
-    // skip event logging diskstats when it is zero increment (all first 11 entries are zero)
-    if (memcmp(&zero_cmp, stats, sizeof(uint64_t) * DISK_STATS_SIZE) == 0) return;
-
-    android_log_event_list(EVENTLOGTAG_DISKSTATS)
-        << type << stats->start_time << stats->end_time
-        << stats->read_ios << stats->read_merges
-        << stats->read_sectors << stats->read_ticks
-        << stats->write_ios << stats->write_merges
-        << stats->write_sectors << stats->write_ticks
-        << (uint64_t)stats->io_avg << stats->io_ticks << stats->io_in_queue
-        << LOG_ID_EVENTS;
-}
-
diff --git a/storaged/tests/storaged_test.cpp b/storaged/tests/storaged_test.cpp
index b103ac1..bd14d76 100644
--- a/storaged/tests/storaged_test.cpp
+++ b/storaged/tests/storaged_test.cpp
@@ -30,7 +30,9 @@
 #define MMC_DISK_STATS_PATH "/sys/block/mmcblk0/stat"
 #define SDA_DISK_STATS_PATH "/sys/block/sda/stat"
 
-static void pause(uint32_t sec) {
+namespace {
+
+void write_and_pause(uint32_t sec) {
     const char* path = "/cache/test";
     int fd = open(path, O_WRONLY | O_CREAT, 0600);
     ASSERT_LT(-1, fd);
@@ -53,6 +55,8 @@
     sleep(sec);
 }
 
+} // namespace
+
 // the return values of the tested functions should be the expected ones
 const char* DISK_STATS_PATH;
 TEST(storaged_test, retvals) {
@@ -77,13 +81,11 @@
     EXPECT_FALSE(parse_disk_stats(wrong_path, &stats));
 
     // reading a wrong path should not damage the output structure
-    EXPECT_EQ(0, memcmp(&stats, &old_stats, sizeof(disk_stats)));
+    EXPECT_EQ(stats, old_stats);
 }
 
 TEST(storaged_test, disk_stats) {
-    struct disk_stats stats;
-    memset(&stats, 0, sizeof(struct disk_stats));
-
+    struct disk_stats stats = {};
     ASSERT_TRUE(parse_disk_stats(DISK_STATS_PATH, &stats));
 
     // every entry of stats (except io_in_flight) should all be greater than 0
@@ -93,11 +95,7 @@
     }
 
     // accumulation of the increments should be the same with the overall increment
-    struct disk_stats base, tmp, curr, acc, inc[5];
-    memset(&base, 0, sizeof(struct disk_stats));
-    memset(&tmp, 0, sizeof(struct disk_stats));
-    memset(&acc, 0, sizeof(struct disk_stats));
-
+    struct disk_stats base = {}, tmp = {}, curr, acc = {}, inc[5];
     for (uint i = 0; i < 5; ++i) {
         ASSERT_TRUE(parse_disk_stats(DISK_STATS_PATH, &curr));
         if (i == 0) {
@@ -106,22 +104,18 @@
             sleep(5);
             continue;
         }
-        inc[i] = get_inc_disk_stats(&tmp, &curr);
+        get_inc_disk_stats(&tmp, &curr, &inc[i]);
         add_disk_stats(&inc[i], &acc);
         tmp = curr;
-        pause(5);
+        write_and_pause(5);
     }
-    struct disk_stats overall_inc;
-    memset(&overall_inc, 0, sizeof(disk_stats));
-    overall_inc= get_inc_disk_stats(&base, &curr);
+    struct disk_stats overall_inc = {};
+    get_inc_disk_stats(&base, &curr, &overall_inc);
 
-    for (uint i = 0; i < DISK_STATS_SIZE; ++i) {
-        if (i == 8) continue; // skip io_in_flight which can be 0
-        EXPECT_EQ(*((uint64_t*)&overall_inc + i), *((uint64_t*)&acc + i));
-    }
+    EXPECT_EQ(overall_inc, acc);
 }
 
-static double mean(std::deque<uint32_t> nums) {
+double mean(std::deque<uint32_t> nums) {
     double sum = 0.0;
     for (uint32_t i : nums) {
     sum += i;
@@ -129,7 +123,7 @@
     return sum / nums.size();
 }
 
-static double standard_deviation(std::deque<uint32_t> nums) {
+double standard_deviation(std::deque<uint32_t> nums) {
     double sum = 0.0;
     double avg = mean(nums);
     for (uint32_t i : nums) {
@@ -181,7 +175,7 @@
     }
 }
 
-static struct disk_perf disk_perf_multiply(struct disk_perf perf, double mul) {
+struct disk_perf disk_perf_multiply(struct disk_perf perf, double mul) {
     struct disk_perf retval;
     retval.read_perf = (double)perf.read_perf * mul;
     retval.read_ios = (double)perf.read_ios * mul;
@@ -192,7 +186,7 @@
     return retval;
 }
 
-static struct disk_stats disk_stats_add(struct disk_stats stats1, struct disk_stats stats2) {
+struct disk_stats disk_stats_add(struct disk_stats stats1, struct disk_stats stats2) {
     struct disk_stats retval;
     retval.read_ios = stats1.read_ios + stats2.read_ios;
     retval.read_merges = stats1.read_merges + stats2.read_merges;
@@ -210,6 +204,30 @@
     return retval;
 }
 
+void expect_increasing(struct disk_stats stats1, struct disk_stats stats2) {
+    EXPECT_LE(stats1.read_ios, stats2.read_ios);
+    EXPECT_LE(stats1.read_merges, stats2.read_merges);
+    EXPECT_LE(stats1.read_sectors, stats2.read_sectors);
+    EXPECT_LE(stats1.read_ticks, stats2.read_ticks);
+    EXPECT_LE(stats1.write_ios, stats2.write_ios);
+    EXPECT_LE(stats1.write_merges, stats2.write_merges);
+    EXPECT_LE(stats1.write_sectors, stats2.write_sectors);
+    EXPECT_LE(stats1.write_ticks, stats2.write_ticks);
+    EXPECT_LE(stats1.io_ticks, stats2.io_ticks);
+    EXPECT_LE(stats1.io_in_queue, stats2.io_in_queue);
+
+    EXPECT_TRUE(stats1.read_ios < stats2.read_ios ||
+        stats1.read_merges < stats2.read_merges ||
+        stats1.read_sectors < stats2.read_sectors ||
+        stats1.read_ticks < stats2.read_ticks ||
+        stats1.write_ios < stats2.write_ios ||
+        stats1.write_merges < stats2.write_merges ||
+        stats1.write_sectors < stats2.write_sectors ||
+        stats1.write_ticks < stats2.write_ticks ||
+        stats1.io_ticks < stats2.io_ticks ||
+        stats1.io_in_queue < stats2.io_in_queue);
+}
+
 TEST(storaged_test, disk_stats_monitor) {
     // asserting that there is one file for diskstats
     ASSERT_TRUE(access(MMC_DISK_STATS_PATH, R_OK) >= 0 || access(SDA_DISK_STATS_PATH, R_OK) >= 0);
@@ -294,14 +312,12 @@
         .io_avg = 0
     };
 
-    struct disk_stats stats_base;
-    memset(&stats_base, 0, sizeof(stats_base));
-
+    struct disk_stats stats_base = {};
     int loop_size = 100;
     for (int i = 0; i < loop_size; ++i) {
         stats_base = disk_stats_add(stats_base, norm_inc);
         dsm_acc.update(&stats_base);
-        EXPECT_EQ(dsm_acc.mValid, (uint32_t)(i + 1) >= dsm_acc.mWindow);
+        EXPECT_EQ(dsm_acc.mValid, (uint32_t)i >= dsm_acc.mWindow);
         EXPECT_FALSE(dsm_acc.mStall);
     }
 
@@ -316,36 +332,14 @@
         EXPECT_TRUE(dsm_acc.mValid);
         EXPECT_FALSE(dsm_acc.mStall);
     }
-}
 
-static void expect_increasing(struct disk_stats stats1, struct disk_stats stats2) {
-    EXPECT_LE(stats1.read_ios, stats2.read_ios);
-    EXPECT_LE(stats1.read_merges, stats2.read_merges);
-    EXPECT_LE(stats1.read_sectors, stats2.read_sectors);
-    EXPECT_LE(stats1.read_ticks, stats2.read_ticks);
-
-    EXPECT_LE(stats1.write_ios, stats2.write_ios);
-    EXPECT_LE(stats1.write_merges, stats2.write_merges);
-    EXPECT_LE(stats1.write_sectors, stats2.write_sectors);
-    EXPECT_LE(stats1.write_ticks, stats2.write_ticks);
-
-    EXPECT_LE(stats1.io_ticks, stats2.io_ticks);
-    EXPECT_LE(stats1.io_in_queue, stats2.io_in_queue);
-}
-
-#define TEST_LOOPS 20
-TEST(storaged_test, disk_stats_publisher) {
-    // asserting that there is one file for diskstats
-    ASSERT_TRUE(access(MMC_DISK_STATS_PATH, R_OK) >= 0 || access(SDA_DISK_STATS_PATH, R_OK) >= 0);
-    disk_stats_publisher dsp;
-    struct disk_stats prev;
-    memset(&prev, 0, sizeof(prev));
-
-    for (int i = 0; i < TEST_LOOPS; ++i) {
-        dsp.update();
-        expect_increasing(prev, dsp.mPrevious);
-        prev = dsp.mPrevious;
-        pause(10);
+    struct disk_stats stats_prev = {};
+    loop_size = 10;
+    write_and_pause(5);
+    for (int i = 0; i < loop_size; ++i) {
+        dsm_detect.update();
+        expect_increasing(stats_prev, dsm_detect.mPrevious);
+        stats_prev = dsm_detect.mPrevious;
+        write_and_pause(5);
     }
 }
-