History log of /art/runtime/gc/space/bump_pointer_space.h
Revision Date Author Comments
2cebb24bfc3247d3e9be138a3350106737455918 22-Apr-2015 Mathieu Chartier <mathieuc@google.com> Replace NULL with nullptr

Also fixed some lines that were too long, and a few other minor
details.

Change-Id: I6efba5fb6e03eb5d0a300fddb2a75bf8e2f175cb
4460a84be92b5a94ecfb5c650aef4945ab849c93 09-Mar-2015 Hiroshi Yamauchi <yamauchi@google.com> Rosalloc thread local allocation path without a cas.

Speedup on N4:
MemAllocTest 3044 -> 2396 (~21% reduction)
BinaryTrees 4101 -> 2929 (~26% reduction)

Bug: 9986565
Change-Id: Ia1d1a37b9e001f903c3c056e8ec68fc8c623a78b
575e78c41ece0dec969d31f46be563d4eb7ae43b 04-Nov-2014 Andreas Gampe <agampe@google.com> ART: Replace COMPILE_ASSERT with static_assert (runtime)

Replace all occurrences of COMPILE_ASSERT in the runtime tree.

Change-Id: I01e420899c760094fb342cc6cb9e692dd670a0b2
13735955f39b3b304c37d2b2840663c131262c18 08-Oct-2014 Ian Rogers <irogers@google.com> stdint types all the way!

Change-Id: I4e4ef3a2002fc59ebd9097087f150eaf3f2a7e08
38c488bcd41ba632a646d7a1d790ec71a2fcf6fa 16-Jul-2014 Mathieu Chartier <mathieuc@google.com> Recycle mem-maps for collector transitions.

We now create spaces when we need them for collector transitions or
homogeneous compaction by recycling mem maps. Change the bump
pointer space size to be as large as the heap capacity instead of
1/2 heap capacity like it used to be. For GSS, bump pointer spaces
are set to 32MB currently.

Changed GSS to have main space == non moving space since we don't
need to copy from the main space.

Fixes GC stress tests 074, 096.
Fixed test 080 oom throw with -Xmx2m for GC stress test, this was
broken since it was allocating a 4 MB array before starting the
OOM process.

Bug: 14059466
Bug: 16406852

(cherry picked from commit b363f666883860d40823d5528df3c98c897f74f4)

Change-Id: I62877cfa24ec944a6f34ffac30334f454a8002fd
b363f666883860d40823d5528df3c98c897f74f4 16-Jul-2014 Mathieu Chartier <mathieuc@google.com> Recycle mem-maps for collector transitions.

We now create spaces when we need them for collector transitions or
homogeneous compaction by recycling mem maps. Change the bump
pointer space size to be as large as the heap capacity instead of
1/2 heap capacity like it used to be. For GSS, bump pointer spaces
are set to 32MB currently.

Changed GSS to have main space == non moving space since we don't
need to copy from the main space.

Fixes GC stress tests 074, 096.
Fixed test 080 oom throw with -Xmx2m for GC stress test, this was
broken since it was allocating a 4 MB array before starting the
OOM process.

Bug: 14059466
Bug: 16406852
Change-Id: I62877cfa24ec944a6f34ffac30334f454a8002fd
52e4b43d62896b56f8c2bd041e528472bb4a0d8d 10-Jun-2014 Mathieu Chartier <mathieuc@google.com> Add mark compact collector.

The mark compact collector is a 4 phase collection, doing a normal
full mark_sweep, calculating forwarding addresses of objects in the
from space, updating references of objects in the from space, and
moving the objects in the from space.

Support is diabled by default since it needs to have non movable
classes and field arrays. Performance numbers is around 50% as fast.

The main advantage that this has over semispace is that the worst
case memory usage is 50% since we only need one space isntead of two.

TODO: Make field arrays and classes movable. This causes complication
since Object::VisitReferences relies on these, so if we update the
fields of an object but another future object uses this object to
figure out what fields are reference fields it doesn't work.

Bug: 14059466

Change-Id: I661ed3b71ad4dde124ef80312c95696b4a5665a1
0651d41e41341fb2e9ef3ee41dc1f1bfc832dbbb 29-Apr-2014 Mathieu Chartier <mathieuc@google.com> Add thread unsafe allocation methods to spaces.

Used by SS/GSS collectors since these run with mutators suspended and
only allocate from a single thread. Added AllocThreadUnsafe to
BumpPointerSpace and RosAllocSpace. Added AllocThreadUnsafe which uses
current runs as thread local runs for a thread unsafe allocation.
Added code to revoke current runs which are the same idx as thread
local runs.

Changed:
The number of thread local runs in each thread is now the the number
of thread local runs in RosAlloc instead of the number of size
brackets.

Total GC time / time on EvaluateAndApplyChanges.
TLAB SS:
Before: 36.7s / 7254
After: 16.1s / 4837

TLAB GSS:
Before: 6.9s / 3973
After: 5.7s / 3778

Bug: 8981901

Change-Id: Id1d264ade3799f431bf7ebbdcca6146aefbeb632
a8e8f9c0a8e259a807d7b99a148d14104c24209d 09-Apr-2014 Mathieu Chartier <mathieuc@google.com> Refactor space bitmap to support different alignments.

Required for:
Using space bitmaps instead of std::set in mod union table +
remembered set.
Using a bitmap instead of set for large object marking.

Bug: 13571028

Change-Id: Id024e9563d4ca4278f79607cdb2f81895121b113
31f441464c0c8f840aba37e236ad133f30308d70 08-Apr-2014 Mathieu Chartier <mathieuc@google.com> Clean-up heap spaces.

We now use the CMS collector instead of the semispace collector when
the phone is booting. We still perform compaction during the zygote
space creation. This reduces time spent in GC by ~2s during boot
and doesn't affect zygote space size.

Changed the space creation logic to create the temp space when a
background transition occurs.

Added a flag to each space which is true if you are allowed to
move objects that are within this space.

Removed SwapSemiSpaces call from the semi space collector, it is now
the job of the caller to do this with threads suspended. This
simplifies the logic in the zygote compaction / heap transition code
since these do not copy from one semispace to another.

Added Space::Clear to RosAllocSpace and DlMallocSpace. This greatly
simplifies the code used for collector transitions.

Time spent in GC creating zygote space:
Before: 3.4s, After: 1.28s
No change in zygote space size.

Bug: 13878055

Change-Id: I700348ab7d5bf3aa537c0cd70c0fed09aa4b0623
c93c530efc175954160c3834c93961a1a946a35a 21-Mar-2014 Hiroshi Yamauchi <yamauchi@google.com> Revoke rosalloc thread-local buffers at the checkpoint.

In the mark sweep collector, rosalloc thread-local buffers were
revoked during the pause. Now, they are revoked at the thread
checkpoint, as opposed to during the pause, which appears to help
reduce the pause time.

In Ritz MemAllocTest, the average sticky pause time went down ~20%
(925 us -> 724 us).

Bug: 13394464
Bug: 9986565
Change-Id: I104992a11b46d59264c0b9aa2db82b1ccf2826bc
719d1a33f6569864f529e5a3fff59e7bca97aad0 06-Mar-2014 Ian Rogers <irogers@google.com> Enable annotalysis on clang ART builds.

Fix clang build errors aswell as restructure locking/mutex code for correct
thread safety analysis support.
Reorder make dependencies so that host builds build first as they should
provide better compilation errors than target.
Remove host's use of -fno-omit-frame-pointer as it has no value with correct
use of CFI, which we should have.

Change-Id: I72cea8da9a3757b1a0b3acb4081feccb7c6cef90
15d3402bbf8265eb1165694da2e4117eb128f3bc 27-Feb-2014 Mathieu Chartier <mathieuc@google.com> Add custom SIGSEGV handler to help find heap corruption.

The new signal handler prints heap diagnostics when you get a SIGSEGV.
Added a fault message member in runtime which is modifiable by
Runtime::SetFaultMessage. When you get a SIGSEGV it will print out
whatever is stored in this string as well as the normal information.
This is useful for debugging heap corruption since it lets you see
which threads were in which methods when the last GC occured.

Added some smarter object dumping logic when the faulting address is
in the heap.

Bug: 12934910

Change-Id: Ia72be2c39f70ad711cbd746d66fad2b617d5d29f
6fac447555dc94a935b78198479cce645c837b89 26-Feb-2014 Ian Rogers <irogers@google.com> Make allocations report usable size.

Work-in-progress to allow arrays to fill usable size. Bug: 13028925.
Use C++11's override keyword on GCC >= 2.7 to ensure that we override GC and
allocator methods.
Move initial mirror::Class set up into a Functor so that all allocated objects
have non-zero sizes. Use this property to assert that all objects are never
larger than their usable size.
Other bits of GC related clean-up, missing initialization, missing use of
const, hot methods in .cc files, "unimplemented" functions that fail at
runtime in header files, reducing header file includes, move valgrind's space
into its own files, reduce number of array allocation routines.

Change-Id: Id5760041a2d7f94dcaf17ec760f6095ec75dadaa
fc4c27e4d68707271bd7578ae5c8bef93a3ea66b 11-Feb-2014 Mathieu Chartier <mathieuc@google.com> Change BumpPointerSpace main block header to not be in space data.

Changed the bump pointer space main block to be in the space and not
the space data. This lets us access the main block header when the
space is protected and lets us walk a protected space as long as it
is empty.

Bug: 12966354
Change-Id: Id53bf59224926718af7356dd9fc1205ff91cc5d1
83c8ee000d525017ead8753fce6bc1020249b96a 28-Jan-2014 Mathieu Chartier <mathieuc@google.com> Add root types and thread id to root visiting.

Enables us to pass the root type and thread id to hprof.

Bug: 12680863
Change-Id: I6a0f1f9e3aa8f9b4033d695818ae7ca3460d67cb
ef7d42fca18c16fbaf103822ad16f23246e2905d 06-Jan-2014 Ian Rogers <irogers@google.com> Object model changes to support 64bit.

Modify mirror objects so that references between them use an ObjectReference
value type rather than an Object* so that functionality to compress larger
references can be captured in the ObjectRefererence implementation.
ObjectReferences are 32bit and all other aspects of object layout remain as
they are currently.

Expand fields in objects holding pointers so they can hold 64bit pointers. Its
expected the size of these will come down by improving where we hold compiler
meta-data.
Stub out x86_64 architecture specific runtime implementation.
Modify OutputStream so that reads and writes are of unsigned quantities.
Make the use of portable or quick code more explicit.
Templatize AtomicInteger to support more than just int32_t as a type.
Add missing, and fix issues relating to, missing annotalysis information on the
mutator lock.
Refactor and share implementations for array copy between System and uses
elsewhere in the runtime.
Fix numerous 64bit build issues.

Change-Id: I1a5694c251a42c9eff71084dfdd4b51fff716822
e6da9af8dfe0a3e3fbc2be700554f6478380e7b9 16-Dec-2013 Mathieu Chartier <mathieuc@google.com> Background compaction support.

When the process state changes to a state which does not perceives
jank, we copy from the main free-list backed allocation space to
the bump pointer space and enable the semispace allocator.

When we transition back to foreground, we copy back to a free-list
backed space.

Create a seperate non-moving space which only holds non-movable
objects. This enables us to quickly wipe the current alloc space
(DlMalloc / RosAlloc) when we transition to background.

Added multiple alloc space support to the sticky mark sweep GC.

Added a -XX:BackgroundGC option which lets you specify
which GC to use for background apps. Passing in
-XX:BackgroundGC=SS makes the heap compact the heap for apps which
do not perceive jank.

Results:
Simple background foreground test:
0. Reboot phone, unlock.
1. Open browser, click on home.
2. Open calculator, click on home.
3. Open calendar, click on home.
4. Open camera, click on home.
5. Open clock, click on home.
6. adb shell dumpsys meminfo

PSS Normal ART:
Sample 1:
88468 kB: Dalvik
3188 kB: Dalvik Other
Sample 2:
81125 kB: Dalvik
3080 kB: Dalvik Other

PSS Dalvik:
Total PSS by category:
Sample 1:
81033 kB: Dalvik
27787 kB: Dalvik Other
Sample 2:
81901 kB: Dalvik
28869 kB: Dalvik Other

PSS ART + Background Compaction:
Sample 1:
71014 kB: Dalvik
1412 kB: Dalvik Other
Sample 2:
73859 kB: Dalvik
1400 kB: Dalvik Other

Dalvik other reduction can be explained by less deep allocation
stacks / less live bitmaps / less dirty cards.

TODO improvements: Recycle mem-maps which are unused in the current
state. Not hardcode 64 MB capacity of non movable space (avoid
returning linear alloc nightmares). Figure out ways to deal with low
virtual address memory problems.

Bug: 8981901

Change-Id: Ib235d03f45548ffc08a06b8ae57bf5bada49d6f3
692fafd9778141fa6ef0048c9569abd7ee0253bf 30-Nov-2013 Mathieu Chartier <mathieuc@google.com> Thread local bump pointer allocator.

Added a thread local allocator to the heap, each thread has three
pointers which specify the thread local buffer: start, cur, and
end. When the remaining space in the thread local buffer isn't large
enough for the allocation, the allocator allocates a new thread
local buffer using the bump pointer allocator.

The bump pointer space had to be modified to accomodate thread
local buffers. These buffers are called "blocks", where a block
is a buffer which contains a set of adjacent objects. Blocks
aren't necessarily full and may have wasted memory towards the
end. Blocks have an 8 byte header which specifies their size and is
required for traversing bump pointer spaces.

Memory usage is in between full bump pointer and ROSAlloc since
madvised memory limits wasted ram to an average of 1/2 page per
block.

Added a runtime option -XX:UseTLAB which specifies whether or
not to use the thread local allocator. Its a NOP if the garbage
collector is not the semispace collector.

TODO: Smarter block accounting to prevent us reading objects until
we either hit the end of the block or GetClass() == null which
signifies that the block isn't 100% full. This would provide a
slight speedup to BumpPointerSpace::Walk.

Timings: -XX:HeapMinFree=4m -XX:HeapMaxFree=8m -Xmx48m
ritzperf memalloc:
Dalvik -Xgc:concurrent: 11678
Dalvik -Xgc:noconcurrent: 6697
-Xgc:MS: 5978
-Xgc:SS: 4271
-Xgc:CMS: 4150
-Xgc:SS -XX:UseTLAB: 3255

Bug: 9986565
Bug: 12042213

Change-Id: Ib7e1d4b199a8199f3b1de94b0a7b6e1730689cad
7410f29b4dae223befac036ea567d7f33351dad1 24-Nov-2013 Mathieu Chartier <mathieuc@google.com> Fix dumpsys meminfo <pid>.

Added a case for BumpPointerSpaces. Confirmed working non-debug.
Should also work in debug builds.

Bug: 11830794
Change-Id: I12053ff16eec403dcd4a780e13095e3212a77132
cbb2d20bea2861f244da2e2318d8c088300a3710 15-Nov-2013 Mathieu Chartier <mathieuc@google.com> Refactor allocation entrypoints.

Adds support for switching entrypoints during runtime. Enables
addition of new allocators with out requiring significant copy
paste. Slight speedup on ritzperf probably due to more inlining.

TODO: Ensuring that the entire allocation path is inlined so
that the switch statement in the allocation code is optimized
out.

Rosalloc measurements:
4583
4453
4439
4434
4751

After change:
4184
4287
4131
4335
4097

Change-Id: I1352a3cbcdf6dae93921582726324d91312df5c9
590fee9e8972f872301c2d16a575d579ee564bee 13-Sep-2013 Mathieu Chartier <mathieuc@google.com> Compacting collector.

The compacting collector is currently similar to semispace. It works by
copying objects back and forth between two bump pointer spaces. There
are types of objects which are "non-movable" due to current runtime
limitations. These are Classes, Methods, and Fields.

Bump pointer spaces are a new type of continuous alloc space which have
no lock in the allocation code path. When you allocate from these it uses
atomic operations to increase an index. Traversing the objects in the bump
pointer space relies on Object::SizeOf matching the allocated size exactly.

Runtime changes:
JNI::GetArrayElements returns copies objects if you attempt to get the
backing data of a movable array. For GetArrayElementsCritical, we return
direct backing storage for any types of arrays, but temporarily disable
the GC until the critical region is completed.

Added a new runtime call called VisitObjects, this is used in place of
the old pattern which was flushing the allocation stack and walking
the bitmaps.

Changed image writer to be compaction safe and use object monitor word
for forwarding addresses.

Added a bunch of added SIRTs to ClassLinker, MethodLinker, etc..

TODO: Enable switching allocators, compacting on background, etc..

Bug: 8981901

Change-Id: I3c886fd322a6eef2b99388d19a765042ec26ab99