MemoryPressureHandlerCocoa.mm [plain text]
/*
* Copyright (C) 2011-2017 Apple Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#import "config.h"
#import "MemoryPressureHandler.h"
#import <mach/mach.h>
#import <mach/task_info.h>
#import <malloc/malloc.h>
#import <notify.h>
#define ENABLE_FMW_FOOTPRINT_COMPARISON 0
extern "C" void cache_simulate_memory_warning_event(uint64_t);
namespace WTF {
void MemoryPressureHandler::platformReleaseMemory(Critical critical)
{
if (critical == Critical::Yes && (!isUnderMemoryPressure() || m_isSimulatingMemoryPressure)) {
// libcache listens to OS memory notifications, but for process suspension
// or memory pressure simulation, we need to prod it manually:
cache_simulate_memory_warning_event(DISPATCH_MEMORYPRESSURE_CRITICAL);
}
}
static dispatch_source_t _cache_event_source = 0;
static dispatch_source_t _timer_event_source = 0;
static int _notifyTokens[3];
// Disable memory event reception for a minimum of s_minimumHoldOffTime
// seconds after receiving an event. Don't let events fire any sooner than
// s_holdOffMultiplier times the last cleanup processing time. Effectively
// this is 1 / s_holdOffMultiplier percent of the time.
// These value seems reasonable and testing verifies that it throttles frequent
// low memory events, greatly reducing CPU usage.
static const Seconds s_minimumHoldOffTime { 5_s };
#if !PLATFORM(IOS)
static const unsigned s_holdOffMultiplier = 20;
#endif
void MemoryPressureHandler::install()
{
if (m_installed || _timer_event_source)
return;
dispatch_async(dispatch_get_main_queue(), ^{
#if PLATFORM(IOS)
_cache_event_source = dispatch_source_create(DISPATCH_SOURCE_TYPE_MEMORYPRESSURE, 0, DISPATCH_MEMORYPRESSURE_NORMAL | DISPATCH_MEMORYPRESSURE_WARN | DISPATCH_MEMORYPRESSURE_CRITICAL, dispatch_get_main_queue());
#elif PLATFORM(MAC)
_cache_event_source = dispatch_source_create(DISPATCH_SOURCE_TYPE_MEMORYPRESSURE, 0, DISPATCH_MEMORYPRESSURE_CRITICAL, dispatch_get_main_queue());
#endif
dispatch_set_context(_cache_event_source, this);
dispatch_source_set_event_handler(_cache_event_source, ^{
bool critical = true;
#if PLATFORM(IOS)
unsigned long status = dispatch_source_get_data(_cache_event_source);
critical = status == DISPATCH_MEMORYPRESSURE_CRITICAL;
auto& memoryPressureHandler = MemoryPressureHandler::singleton();
bool wasCritical = memoryPressureHandler.isUnderMemoryPressure();
memoryPressureHandler.setUnderMemoryPressure(critical);
if (status == DISPATCH_MEMORYPRESSURE_NORMAL) {
if (ReliefLogger::loggingEnabled())
NSLog(@"System is no longer under (%s) memory pressure.", wasCritical ? "critical" : "non-critical");
return;
}
if (ReliefLogger::loggingEnabled())
NSLog(@"Got memory pressure notification (%s)", critical ? "critical" : "non-critical");
#endif
MemoryPressureHandler::singleton().respondToMemoryPressure(critical ? Critical::Yes : Critical::No);
});
dispatch_resume(_cache_event_source);
});
// Allow simulation of memory pressure with "notifyutil -p org.WebKit.lowMemory"
notify_register_dispatch("org.WebKit.lowMemory", &_notifyTokens[0], dispatch_get_main_queue(), ^(int) {
#if ENABLE(FMW_FOOTPRINT_COMPARISON)
auto footprintBefore = pagesPerVMTag();
#endif
beginSimulatedMemoryPressure();
WTF::releaseFastMallocFreeMemory();
malloc_zone_pressure_relief(nullptr, 0);
#if ENABLE(FMW_FOOTPRINT_COMPARISON)
auto footprintAfter = pagesPerVMTag();
logFootprintComparison(footprintBefore, footprintAfter);
#endif
dispatch_async(dispatch_get_main_queue(), ^{
endSimulatedMemoryPressure();
});
});
notify_register_dispatch("org.WebKit.lowMemory.begin", &_notifyTokens[1], dispatch_get_main_queue(), ^(int) {
beginSimulatedMemoryPressure();
});
notify_register_dispatch("org.WebKit.lowMemory.end", &_notifyTokens[2], dispatch_get_main_queue(), ^(int) {
endSimulatedMemoryPressure();
});
m_installed = true;
}
void MemoryPressureHandler::uninstall()
{
if (!m_installed)
return;
dispatch_async(dispatch_get_main_queue(), ^{
if (_cache_event_source) {
dispatch_source_cancel(_cache_event_source);
_cache_event_source = 0;
}
if (_timer_event_source) {
dispatch_source_cancel(_timer_event_source);
_timer_event_source = 0;
}
});
m_installed = false;
for (auto& token : _notifyTokens)
notify_cancel(token);
}
void MemoryPressureHandler::holdOff(Seconds seconds)
{
dispatch_async(dispatch_get_main_queue(), ^{
_timer_event_source = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatch_get_main_queue());
if (_timer_event_source) {
dispatch_set_context(_timer_event_source, this);
// FIXME: The final argument `s_minimumHoldOffTime.seconds()` seems wrong.
// https://bugs.webkit.org/show_bug.cgi?id=183277
dispatch_source_set_timer(_timer_event_source, dispatch_time(DISPATCH_TIME_NOW, seconds.seconds() * NSEC_PER_SEC), DISPATCH_TIME_FOREVER, s_minimumHoldOffTime.seconds());
dispatch_source_set_event_handler(_timer_event_source, ^{
if (_timer_event_source) {
dispatch_source_cancel(_timer_event_source);
_timer_event_source = 0;
}
MemoryPressureHandler::singleton().install();
});
dispatch_resume(_timer_event_source);
}
});
}
void MemoryPressureHandler::respondToMemoryPressure(Critical critical, Synchronous synchronous)
{
#if !PLATFORM(IOS)
uninstall();
MonotonicTime startTime = MonotonicTime::now();
#endif
releaseMemory(critical, synchronous);
#if !PLATFORM(IOS)
Seconds holdOffTime = (MonotonicTime::now() - startTime) * s_holdOffMultiplier;
holdOff(std::max(holdOffTime, s_minimumHoldOffTime));
#endif
}
std::optional<MemoryPressureHandler::ReliefLogger::MemoryUsage> MemoryPressureHandler::ReliefLogger::platformMemoryUsage()
{
task_vm_info_data_t vmInfo;
mach_msg_type_number_t count = TASK_VM_INFO_COUNT;
kern_return_t err = task_info(mach_task_self(), TASK_VM_INFO, (task_info_t) &vmInfo, &count);
if (err != KERN_SUCCESS)
return std::nullopt;
return MemoryUsage {static_cast<size_t>(vmInfo.internal), static_cast<size_t>(vmInfo.phys_footprint)};
}
} // namespace WTF