From a3aaaaf1c84c68c3c6804b369611224a1a04db64 Mon Sep 17 00:00:00 2001 From: erikchen Date: Mon, 2 Nov 2015 11:46:06 -0800 Subject: reland 3: "mac: Run A/B experiment on SharedMemory mechanism for resource buffers." The second reland still induced flaky crashes in GPU conformance tests related to over-releasing a scoped_refptr. This CL should have fixed the problem: https://codereview.chromium.org/1408793008/. I can reproduce the failure non-deterministically locally. I get a crash every 2-3 runs of the ogles conformance tests. With the CL I mentioned above, I've had 20 runs with no crashes. > The CL changes the default behavior of resource buffer to use a Mach-backed > SharedMemory region. This CL adds a field trial to measure the effect of Mach vs > POSIX backed SharedMemory regions. > > BUG=547261, 466437 > Committed: https://crrev.com/e0e2fd398f3d07c8eebbe662d71a0f9286862476 > Cr-Commit-Position: refs/heads/master@{#356513} BUG=547261, 466437 TBR=mark@chromium.org, isherman@chromium.org, asvitkine@chromium.org, avi@chromium.org Review URL: https://codereview.chromium.org/1420203008 Cr-Commit-Position: refs/heads/master@{#357407} --- base/memory/shared_memory.h | 4 +++ base/memory/shared_memory_handle.h | 3 +++ base/memory/shared_memory_mac.cc | 53 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 60 insertions(+) (limited to 'base') diff --git a/base/memory/shared_memory.h b/base/memory/shared_memory.h index 18416c0..5cdcb0d 100644 --- a/base/memory/shared_memory.h +++ b/base/memory/shared_memory.h @@ -140,6 +140,10 @@ class BASE_EXPORT SharedMemory { // http://crbug.com/466437. bool CreateAndMapAnonymousPosix(size_t size); bool CreateAnonymousPosix(size_t size); + + // This method is an analog of CreateAndMapAnonymous that forces the + // underlying OS primitive to be a Mach memory object. + bool CreateAndMapAnonymousMach(size_t size); #endif // defined(OS_MACOSX) && !defined(OS_IOS) // Creates an anonymous shared memory segment of size size. diff --git a/base/memory/shared_memory_handle.h b/base/memory/shared_memory_handle.h index b3dfc8f..49398a4 100644 --- a/base/memory/shared_memory_handle.h +++ b/base/memory/shared_memory_handle.h @@ -75,12 +75,15 @@ class BASE_EXPORT SharedMemoryHandle { #else class BASE_EXPORT SharedMemoryHandle { public: + // The values of these enums must not change, as they are used by the + // histogram OSX.SharedMemory.Mechanism. enum Type { // The SharedMemoryHandle is backed by a POSIX fd. POSIX, // The SharedMemoryHandle is backed by the Mach primitive "memory object". MACH, }; + static const int TypeMax = 2; // The format that should be used to transmit |Type| over the wire. typedef int TypeWireFormat; diff --git a/base/memory/shared_memory_mac.cc b/base/memory/shared_memory_mac.cc index 799b8e3..8f198dc 100644 --- a/base/memory/shared_memory_mac.cc +++ b/base/memory/shared_memory_mac.cc @@ -13,7 +13,10 @@ #include "base/files/file_util.h" #include "base/files/scoped_file.h" #include "base/logging.h" +#include "base/mac/mac_util.h" #include "base/mac/scoped_mach_vm.h" +#include "base/metrics/field_trial.h" +#include "base/metrics/histogram_macros.h" #include "base/posix/eintr_wrapper.h" #include "base/posix/safe_strerror.h" #include "base/process/process_metrics.h" @@ -29,6 +32,38 @@ namespace base { namespace { +const char kTrialName[] = "MacMemoryMechanism"; +const char kTrialMach[] = "Mach"; +const char kTrialPosix[] = "Posix"; + +SharedMemoryHandle::Type GetABTestMechanism() { + static bool found_group = false; + static SharedMemoryHandle::Type group = SharedMemoryHandle::MACH; + + if (found_group) + return group; + + const std::string group_name = + base::FieldTrialList::FindFullName(kTrialName); + if (group_name == kTrialMach) { + group = SharedMemoryHandle::MACH; + found_group = true; + } else if (group_name == kTrialPosix) { + group = SharedMemoryHandle::POSIX; + found_group = true; + } else { + group = SharedMemoryHandle::MACH; + } + + return group; +} + +// Emits a histogram entry indicating which type of SharedMemory was created. +void EmitMechanism(SharedMemoryHandle::Type type) { + UMA_HISTOGRAM_ENUMERATION("OSX.SharedMemory.Mechanism", type, + SharedMemoryHandle::TypeMax); +} + // Returns whether the operation succeeded. // |new_handle| is an output variable, populated on success. The caller takes // ownership of the underlying memory object. @@ -227,6 +262,22 @@ bool SharedMemory::CreateAnonymousPosix(size_t size) { return Create(options); } +bool SharedMemory::CreateAndMapAnonymousMach(size_t size) { + SharedMemoryCreateOptions options; + + if (mac::IsOSLionOrLater()) { + // A/B test the mechanism. Once the experiment is over, this will always be + // set to SharedMemoryHandle::MACH. + // http://crbug.com/547261 + options.type = GetABTestMechanism(); + } else { + // Mach shared memory isn't supported on OSX 10.6 or older. + options.type = SharedMemoryHandle::POSIX; + } + options.size = size; + return Create(options) && Map(size); +} + // static bool SharedMemory::GetSizeFromSharedMemoryHandle( const SharedMemoryHandle& handle, @@ -248,6 +299,8 @@ bool SharedMemory::Create(const SharedMemoryCreateOptions& options) { if (options.size > static_cast(std::numeric_limits::max())) return false; + EmitMechanism(options.type); + if (options.type == SharedMemoryHandle::MACH) { shm_ = SharedMemoryHandle(options.size); requested_size_ = options.size; -- cgit v1.1