ART: Compacting ROS/DlMalloc spaces with semispace copy GC
Current semispace copy GC is mainly associated with bump pointer
spaces. Though it squeezes fragmentation most aggressively, an extra
copy is required to re-establish the data in the ROS/DlMalloc space to allow
CMS GCs to happen afterwards. As semispace copy GC is still stop-the-world,
this not only introduces unnecessary overheads but also longer response time.
Response time indicates the time duration between the start of transition
request and the start of transition animation, which may impact the user
experience.
Using semispace copy GC to compact the data in a ROS space to another ROS(or
DlMalloc space to another DlMalloc) space solves this problem. Although it
squeezes less fragmentation, CMS GCs can run immediately after the compaction.
We apply this algorithm in two cases:
1) Right before throwing an OOM if -XX:EnableHSpaceCompactForOOM is passed in
as true.
2) When app is switched to background if the -XX:BackgroundGC option has value
HSpaceCompact.
For case 1), OOMs are significantly delayed in the harmony GC stress test,
with compaction ratio up to 0.87. For case 2), compaction ratio around 0.5 is
observed in both built-in SMS and browser. Similar results have been obtained
on other apps as well.
Change-Id: Iad9eabc6d046659fda3535ae20f21bc31f89ded3
Signed-off-by: Wang, Zuo <zuo.wang@intel.com>
Signed-off-by: Chang, Yang <yang.chang@intel.com>
Signed-off-by: Lei Li <lei.l.li@intel.com>
Signed-off-by: Lin Zang <lin.zang@intel.com>
diff --git a/runtime/parsed_options.h b/runtime/parsed_options.h
index d0f3c12..4c74be6 100644
--- a/runtime/parsed_options.h
+++ b/runtime/parsed_options.h
@@ -88,6 +88,12 @@
static constexpr uint32_t kExplicitSuspendCheck = 2;
static constexpr uint32_t kExplicitStackOverflowCheck = 4;
uint32_t explicit_checks_;
+ // Whether or not we use homogeneous space compaction to avoid OOM errors. If enabled,
+ // the heap will attempt to create an extra space which enables compacting from a malloc space to
+ // another malloc space when we are about to throw OOM.
+ bool use_homogeneous_space_compaction_for_oom_;
+ // Minimal interval allowed between two homogeneous space compactions caused by OOM.
+ uint64_t min_interval_homogeneous_space_compaction_by_oom_;
private:
ParsedOptions() {}