meminfo: Add IsSmapsRollupSupported Api
Consolidate the checking of /proc/<pid>/smaps_rollup support
in libmeminfo and do it in a thread safe way.
Use the API in ProcMemInfo as well to eliminate the extra
parameters passed to SmapsOrRollup* methods.
Bug: 111694435
Test: libmeminfo_test 1 --gtest_filter=TestProcMemInfo.IsSmapsSupportedTest
Test: Tested with and without the smaps_rollup support in kernel.
Change-Id: I992057f06b54569025fa0cdade9618da2675d1de
Merged-In: I992057f06b54569025fa0cdade9618da2675d1de
Signed-off-by: Sandeep Patil <sspatil@google.com>
diff --git a/libmeminfo/include/meminfo/procmeminfo.h b/libmeminfo/include/meminfo/procmeminfo.h
index 4cce133..0b66074 100644
--- a/libmeminfo/include/meminfo/procmeminfo.h
+++ b/libmeminfo/include/meminfo/procmeminfo.h
@@ -64,12 +64,12 @@
// private_dirty
// SwapPss
// All other fields of MemUsage are zeroed.
- bool SmapsOrRollup(bool use_rollup, MemUsage* stats) const;
+ bool SmapsOrRollup(MemUsage* stats) const;
// Used to parse either of /proc/<pid>/{smaps, smaps_rollup} and record the process's
- // Pss. The 'use_rollup' parameter decides which file is to be tried.
+ // Pss.
// Returns 'true' on success and the value of Pss in the out parameter.
- bool SmapsOrRollupPss(bool use_rollup, uint64_t* pss) const;
+ bool SmapsOrRollupPss(uint64_t* pss) const;
const std::vector<uint16_t>& SwapOffsets();
@@ -94,6 +94,12 @@
// same format as /proc/<pid>/smaps. Returns 'false' if the file is malformed.
bool ForEachVmaFromFile(const std::string& path, const VmaCallback& callback);
+// Returns if the kernel supports /proc/<pid>/smaps_rollup. Assumes that the
+// calling process has access to the /proc/<pid>/smaps_rollup.
+// Returns 'false' if the calling process has no permission to read the file if it exists
+// of if the file doesn't exist.
+bool IsSmapsRollupSupported(pid_t pid);
+
// Same as ProcMemInfo::SmapsOrRollup but reads the statistics directly
// from a file. The file MUST be in the same format as /proc/<pid>/smaps
// or /proc/<pid>/smaps_rollup
diff --git a/libmeminfo/libmeminfo_test.cpp b/libmeminfo/libmeminfo_test.cpp
index 796a7d0..e689a26 100644
--- a/libmeminfo/libmeminfo_test.cpp
+++ b/libmeminfo/libmeminfo_test.cpp
@@ -284,13 +284,22 @@
EXPECT_EQ(swap_offsets.size(), 0);
}
+TEST(TestProcMemInfo, IsSmapsSupportedTest) {
+ std::string path = ::android::base::StringPrintf("/proc/%d/smaps_rollup", pid);
+ bool supported = IsSmapsRollupSupported(pid);
+ EXPECT_EQ(!access(path.c_str(), F_OK | R_OK), supported);
+ // Second call must return what the first one returned regardless of the pid parameter.
+ // So, deliberately pass invalid pid.
+ EXPECT_EQ(supported, IsSmapsRollupSupported(-1));
+}
+
TEST(TestProcMemInfo, SmapsOrRollupReturn) {
// if /proc/<pid>/smaps_rollup file exists, .SmapsRollup() must return true;
// false otherwise
std::string path = ::android::base::StringPrintf("/proc/%d/smaps_rollup", pid);
ProcMemInfo proc_mem(pid);
MemUsage stats;
- EXPECT_EQ(!access(path.c_str(), F_OK), proc_mem.SmapsOrRollup(true, &stats));
+ EXPECT_EQ(!access(path.c_str(), F_OK), proc_mem.SmapsOrRollup(&stats));
}
TEST(TestProcMemInfo, SmapsOrRollupTest) {
diff --git a/libmeminfo/procmeminfo.cpp b/libmeminfo/procmeminfo.cpp
index f72d469..347a293 100644
--- a/libmeminfo/procmeminfo.cpp
+++ b/libmeminfo/procmeminfo.cpp
@@ -21,6 +21,7 @@
#include <stdio.h>
#include <unistd.h>
+#include <atomic>
#include <fstream>
#include <iostream>
#include <memory>
@@ -172,15 +173,15 @@
return ForEachVmaFromFile(path, callback);
}
-bool ProcMemInfo::SmapsOrRollup(bool use_rollup, MemUsage* stats) const {
- std::string path = ::android::base::StringPrintf("/proc/%d/%s", pid_,
- use_rollup ? "smaps_rollup" : "smaps");
+bool ProcMemInfo::SmapsOrRollup(MemUsage* stats) const {
+ std::string path = ::android::base::StringPrintf(
+ "/proc/%d/%s", pid_, IsSmapsRollupSupported(pid_) ? "smaps_rollup" : "smaps");
return SmapsOrRollupFromFile(path, stats);
-};
+}
-bool ProcMemInfo::SmapsOrRollupPss(bool use_rollup, uint64_t* pss) const {
- std::string path = ::android::base::StringPrintf("/proc/%d/%s", pid_,
- use_rollup ? "smaps_rollup" : "smaps");
+bool ProcMemInfo::SmapsOrRollupPss(uint64_t* pss) const {
+ std::string path = ::android::base::StringPrintf(
+ "/proc/%d/%s", pid_, IsSmapsRollupSupported(pid_) ? "smaps_rollup" : "smaps");
return SmapsOrRollupPssFromFile(path, pss);
}
@@ -374,6 +375,31 @@
return true;
}
+enum smaps_rollup_support { UNTRIED, SUPPORTED, UNSUPPORTED };
+
+static std::atomic<smaps_rollup_support> g_rollup_support = UNTRIED;
+
+bool IsSmapsRollupSupported(pid_t pid) {
+ // Similar to OpenSmapsOrRollup checks from android_os_Debug.cpp, except
+ // the method only checks if rollup is supported and returns the status
+ // right away.
+ enum smaps_rollup_support rollup_support = g_rollup_support.load(std::memory_order_relaxed);
+ if (rollup_support != UNTRIED) {
+ return rollup_support == SUPPORTED;
+ }
+ std::string rollup_file = ::android::base::StringPrintf("/proc/%d/smaps_rollup", pid);
+ if (access(rollup_file.c_str(), F_OK | R_OK)) {
+ // No check for errno = ENOENT necessary here. The caller MUST fallback to
+ // using /proc/<pid>/smaps instead anyway.
+ g_rollup_support.store(UNSUPPORTED, std::memory_order_relaxed);
+ return false;
+ }
+
+ g_rollup_support.store(SUPPORTED, std::memory_order_relaxed);
+ LOG(INFO) << "Using smaps_rollup for pss collection";
+ return true;
+}
+
bool SmapsOrRollupFromFile(const std::string& path, MemUsage* stats) {
auto fp = std::unique_ptr<FILE, decltype(&fclose)>{fopen(path.c_str(), "re"), fclose};
if (fp == nullptr) {