Remove memory_pressure component.

components/memory_pressure/direct_memory_pressure_calculator_linux.cc

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "components/memory_pressure/direct_memory_pressure_calculator_linux.h"
-
-#include "base/files/file_util.h"
-#include "base/process/process_metrics.h"
-#include "base/strings/string_number_conversions.h"
-#include "base/strings/string_split.h"
-#include "base/strings/string_util.h"
-#include "base/sys_info.h"
-#include "base/threading/thread_restrictions.h"
-
-namespace memory_pressure {
-
-namespace {
-
-const int kKiBperMiB = 1024;
-
-// Used to calculate a moving average of faults/sec.  Our sample times are
-// inconsistent because MemoryPressureMonitor calls
-// CalculateCurrentPressureLevel more frequently when memory pressure is high,
-// and because we're measuring CPU time instead of real time.  So our
-// exponentially weighted moving average is generalized to a low-pass filter.
-//
-// Represents the amount of CPU time, in seconds, for a sample to be 50%
-// forgotten in our moving average.  Systems with more CPUs that are under high
-// load will have a moving average that changes more quickly than a system with
-// fewer CPUs under the same load.  Do not normalize based on the number of CPUs
-// because this behavior is accurate:  if a system with a large number of CPUs
-// is getting lots of work done without page faulting, it must not be under
-// memory pressure.
-//
-// TODO(thomasanderson): Experimentally determine the correct value for this
-// constant.
-const double kLowPassHalfLife = 30.0;
-
-// Returns the amount of memory that is available for use right now, or that can
-// be easily reclaimed by the OS, in MBs.
-int GetAvailableSystemMemoryMiB(const base::SystemMemoryInfoKB* mem_info) {
-  return mem_info->available
-             ? mem_info->available / kKiBperMiB
-             : (mem_info->free + mem_info->buffers + mem_info->cached) /
-                   kKiBperMiB;
-}
-
-}  // namespace
-
-// Thresholds at which we consider the system being under moderate/critical
-// memory pressure. They represent the percentage of system memory in use.
-const int DirectMemoryPressureCalculator::kDefaultModerateThresholdPc = 70;
-const int DirectMemoryPressureCalculator::kDefaultCriticalThresholdPc = 90;
-
-DirectMemoryPressureCalculator::DirectMemoryPressureCalculator()
-    : moderate_threshold_mb_(0),
-      critical_threshold_mb_(0) {
-  InferThresholds();
-  InitPageFaultMonitor();
-}
-
-DirectMemoryPressureCalculator::DirectMemoryPressureCalculator(
-    int moderate_threshold_mb,
-    int critical_threshold_mb)
-    : moderate_threshold_mb_(moderate_threshold_mb),
-      critical_threshold_mb_(critical_threshold_mb) {
-  DCHECK_GE(moderate_threshold_mb_, critical_threshold_mb_);
-  DCHECK_LE(0, critical_threshold_mb_);
-  InitPageFaultMonitor();
-}
-
-DirectMemoryPressureCalculator::MemoryPressureLevel
-DirectMemoryPressureCalculator::PressureCausedByThrashing(
-    const base::SystemMemoryInfoKB& mem_info) {
-  base::TimeDelta new_user_exec_time = GetUserCpuTimeSinceBoot();
-  if (new_user_exec_time == base::TimeDelta())
-    return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE;
-  uint64_t new_major_page_faults = mem_info.pgmajfault;
-  if (new_user_exec_time != base::TimeDelta() && new_major_page_faults &&
-      (new_user_exec_time - last_user_exec_time_) != base::TimeDelta()) {
-    double delta_user_exec_time =
-        (new_user_exec_time - last_user_exec_time_).InSecondsF();
-    double delta_major_page_faults =
-        new_major_page_faults - last_major_page_faults_;
-
-    double sampled_faults_per_second =
-        delta_major_page_faults / delta_user_exec_time;
-
-    double adjusted_ewma_coefficient =
-        1 - exp2(-delta_user_exec_time / low_pass_half_life_seconds_);
-
-    current_faults_per_second_ =
-        adjusted_ewma_coefficient * sampled_faults_per_second +
-        (1 - adjusted_ewma_coefficient) * current_faults_per_second_;
-
-    last_user_exec_time_ = new_user_exec_time;
-    last_major_page_faults_ = new_major_page_faults;
-  }
-
-  if (current_faults_per_second_ >
-      critical_multiplier_ * AverageFaultsPerSecond()) {
-    return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL;
-  }
-  if (current_faults_per_second_ >
-      moderate_multiplier_ * AverageFaultsPerSecond()) {
-    return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE;
-  }
-  return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE;
-}
-
-DirectMemoryPressureCalculator::MemoryPressureLevel
-DirectMemoryPressureCalculator::PressureCausedByOOM(
-    const base::SystemMemoryInfoKB& mem_info) {
-  int phys_free = GetAvailableSystemMemoryMiB(&mem_info);
-
-  if (phys_free <= critical_threshold_mb_)
-    return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL;
-  if (phys_free <= moderate_threshold_mb_)
-    return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE;
-  return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE;
-}
-
-DirectMemoryPressureCalculator::MemoryPressureLevel
-DirectMemoryPressureCalculator::CalculateCurrentPressureLevel() {
-  base::SystemMemoryInfoKB mem_info = {};
-  if (!GetSystemMemoryInfo(&mem_info))
-    return MemoryPressureListener::MEMORY_PRESSURE_LEVEL_NONE;
-
-  return std::max(PressureCausedByThrashing(mem_info),
-                  PressureCausedByOOM(mem_info));
-}
-
-bool DirectMemoryPressureCalculator::GetSystemMemoryInfo(
-    base::SystemMemoryInfoKB* mem_info) const {
-  return base::GetSystemMemoryInfo(mem_info);
-}
-
-base::TimeDelta DirectMemoryPressureCalculator::GetUserCpuTimeSinceBoot()
-    const {
-  return base::GetUserCpuTimeSinceBoot();
-}
-
-void DirectMemoryPressureCalculator::InferThresholds() {
-  base::SystemMemoryInfoKB mem_info = {};
-  if (!GetSystemMemoryInfo(&mem_info))
-    return;
-
-  moderate_threshold_mb_ =
-      mem_info.total * (100 - kDefaultModerateThresholdPc) / 100 / kKiBperMiB;
-  critical_threshold_mb_ =
-      mem_info.total * (100 - kDefaultCriticalThresholdPc) / 100 / kKiBperMiB;
-}
-
-void DirectMemoryPressureCalculator::InitPageFaultMonitor() {
-  low_pass_half_life_seconds_ = kLowPassHalfLife;
-  last_user_exec_time_ = GetUserCpuTimeSinceBoot();
-  base::SystemMemoryInfoKB mem_info = {};
-  last_major_page_faults_ =
-      GetSystemMemoryInfo(&mem_info) ? mem_info.pgmajfault : 0;
-  current_faults_per_second_ = AverageFaultsPerSecond();
-}
-
-double DirectMemoryPressureCalculator::AverageFaultsPerSecond() const {
-  return last_major_page_faults_ == 0
-             ? last_user_exec_time_.InSecondsF() / last_major_page_faults_
-             : 0;
-}
-
-}  // namespace memory_pressure