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Bug 1081871 - part 2 - Use cgroups instead of nice values to implement application priorities. r=dhylands

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This commit is contained in:
Gabriele Svelto 2015-01-08 15:39:43 +01:00
parent 72bb309318
commit d800fbc91b
2 changed files with 294 additions and 206 deletions
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43
b2g/app/b2g.js
View File

@ -693,50 +693,57 @@ pref("dom.ipc.processPriorityManager.backgroundLRUPoolLevels", 5);
// Kernel parameters for process priorities. These affect how processes are
// killed on low-memory and their relative CPU priorities.
//
// Note: The maximum nice value on Linux is 19, but the max value you should
// use here is 18. NSPR adds 1 to some threads' nice values, to mark
// low-priority threads. If the process priority manager were to renice a
// process (and all its threads) to 19, all threads would have the same
// niceness. Then when we reniced the process to (say) 10, all threads would
// /still/ have the same niceness; we'd effectively have erased NSPR's thread
// priorities.
// The kernel can only accept 6 (OomScoreAdjust, KillUnderKB) pairs. But it is
// okay, kernel will still kill processes with larger OomScoreAdjust first even
// its OomScoreAdjust don't have a corresponding KillUnderKB.
pref("hal.processPriorityManager.gonk.MASTER.OomScoreAdjust", 0);
pref("hal.processPriorityManager.gonk.MASTER.KillUnderKB", 4096);
pref("hal.processPriorityManager.gonk.MASTER.Nice", 0);
pref("hal.processPriorityManager.gonk.MASTER.cgroup", "");
pref("hal.processPriorityManager.gonk.PREALLOC.OomScoreAdjust", 67);
pref("hal.processPriorityManager.gonk.PREALLOC.Nice", 18);
pref("hal.processPriorityManager.gonk.PREALLOC.cgroup", "apps/bg_non_interactive");
pref("hal.processPriorityManager.gonk.FOREGROUND_HIGH.OomScoreAdjust", 67);
pref("hal.processPriorityManager.gonk.FOREGROUND_HIGH.KillUnderKB", 5120);
pref("hal.processPriorityManager.gonk.FOREGROUND_HIGH.Nice", 0);
pref("hal.processPriorityManager.gonk.FOREGROUND_HIGH.cgroup", "apps/critical");
pref("hal.processPriorityManager.gonk.FOREGROUND.OomScoreAdjust", 134);
pref("hal.processPriorityManager.gonk.FOREGROUND.KillUnderKB", 6144);
pref("hal.processPriorityManager.gonk.FOREGROUND.Nice", 1);
pref("hal.processPriorityManager.gonk.FOREGROUND.cgroup", "apps");
pref("hal.processPriorityManager.gonk.FOREGROUND_KEYBOARD.OomScoreAdjust", 200);
pref("hal.processPriorityManager.gonk.FOREGROUND_KEYBOARD.Nice", 1);
pref("hal.processPriorityManager.gonk.FOREGROUND_KEYBOARD.cgroup", "apps");
pref("hal.processPriorityManager.gonk.BACKGROUND_PERCEIVABLE.OomScoreAdjust", 400);
pref("hal.processPriorityManager.gonk.BACKGROUND_PERCEIVABLE.KillUnderKB", 7168);
pref("hal.processPriorityManager.gonk.BACKGROUND_PERCEIVABLE.Nice", 7);
pref("hal.processPriorityManager.gonk.BACKGROUND_PERCEIVABLE.cgroup", "apps/bg_perceivable");
pref("hal.processPriorityManager.gonk.BACKGROUND_HOMESCREEN.OomScoreAdjust", 534);
pref("hal.processPriorityManager.gonk.BACKGROUND_HOMESCREEN.KillUnderKB", 8192);
pref("hal.processPriorityManager.gonk.BACKGROUND_HOMESCREEN.Nice", 18);
pref("hal.processPriorityManager.gonk.BACKGROUND_HOMESCREEN.cgroup", "apps/bg_non_interactive");
pref("hal.processPriorityManager.gonk.BACKGROUND.OomScoreAdjust", 667);
pref("hal.processPriorityManager.gonk.BACKGROUND.KillUnderKB", 20480);
pref("hal.processPriorityManager.gonk.BACKGROUND.Nice", 18);
pref("hal.processPriorityManager.gonk.BACKGROUND.cgroup", "apps/bg_non_interactive");
// Processes get this niceness when they have low CPU priority.
pref("hal.processPriorityManager.gonk.LowCPUNice", 18);
// Control group definitions (i.e., CPU priority groups) for B2G processes.
// Foreground apps
pref("hal.processPriorityManager.gonk.cgroups.apps.cpu_shares", 1024);
pref("hal.processPriorityManager.gonk.cgroups.apps.cpu_notify_on_migrate", 0);
// Foreground apps with high priority, 16x more CPU than foreground ones
pref("hal.processPriorityManager.gonk.cgroups.apps/critical.cpu_shares", 16384);
pref("hal.processPriorityManager.gonk.cgroups.apps/critical.cpu_notify_on_migrate", 0);
// Background perceivable apps, ~10x less CPU than foreground ones
pref("hal.processPriorityManager.gonk.cgroups.apps/bg_perceivable.cpu_shares", 103);
pref("hal.processPriorityManager.gonk.cgroups.apps/bg_perceivable.cpu_notify_on_migrate", 0);
// Background apps, ~20x less CPU than foreground ones and ~2x less than perceivable ones
pref("hal.processPriorityManager.gonk.cgroups.apps/bg_non_interactive.cpu_shares", 52);
pref("hal.processPriorityManager.gonk.cgroups.apps/bg_non_interactive.cpu_notify_on_migrate", 0);
// By default the compositor thread on gonk runs without real-time priority. RT
// priority can be enabled by setting this pref to a value between 1 and 99.

457
hal/gonk/GonkHal.cpp
View File

@ -24,6 +24,7 @@
#include <sched.h>
#include <stdio.h>
#include <sys/klog.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/resource.h>
#include <time.h>
@ -47,6 +48,7 @@
#include "HalImpl.h"
#include "HalLog.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/ClearOnShutdown.h"
#include "mozilla/dom/battery/Constants.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/FileUtils.h"
@ -1292,6 +1294,261 @@ OomVictimLogger::Observe(
return NS_OK;
}
/**
* Wraps a particular ProcessPriority, giving us easy access to the prefs that
* are relevant to it.
*
* Creating a PriorityClass also ensures that the control group is created.
*/
class PriorityClass
{
public:
/**
* Create a PriorityClass for the given ProcessPriority. This implicitly
* reads the relevant prefs and opens the cgroup.procs file of the relevant
* control group caching its file descriptor for later use.
*/
PriorityClass(ProcessPriority aPriority);
/**
* Closes the file descriptor for the cgroup.procs file of the associated
* control group.
*/
~PriorityClass();
PriorityClass(const PriorityClass& aOther);
PriorityClass& operator=(const PriorityClass& aOther);
ProcessPriority Priority()
{
return mPriority;
}
int32_t OomScoreAdj()
{
return clamped<int32_t>(mOomScoreAdj, OOM_SCORE_ADJ_MIN, OOM_SCORE_ADJ_MAX);
}
int32_t KillUnderKB()
{
return mKillUnderKB;
}
nsCString CGroup()
{
return mGroup;
}
/**
* Adds a process to this priority class, this moves the process' PID into
* the associated control group.
*
* @param aPid The PID of the process to be added.
*/
void AddProcess(int aPid);
private:
ProcessPriority mPriority;
int32_t mOomScoreAdj;
int32_t mKillUnderKB;
int mCGroupProcsFd;
nsCString mGroup;
/**
* Return a string that identifies where we can find the value of aPref
* that's specific to mPriority. For example, we might return
* "hal.processPriorityManager.gonk.FOREGROUND_HIGH.oomScoreAdjust".
*/
nsCString PriorityPrefName(const char* aPref)
{
return nsPrintfCString("hal.processPriorityManager.gonk.%s.%s",
ProcessPriorityToString(mPriority), aPref);
}
/**
* Get the full path of the cgroup.procs file associated with the group.
*/
nsCString CGroupProcsFilename()
{
nsCString cgroupName = mGroup;
/* If mGroup is empty, our cgroup.procs file is the root procs file,
* located at /dev/cpuctl/cgroup.procs. Otherwise our procs file is
* /dev/cpuctl/NAME/cgroup.procs. */
if (!mGroup.IsEmpty()) {
cgroupName.AppendLiteral("/");
}
return NS_LITERAL_CSTRING("/dev/cpuctl/") + cgroupName +
NS_LITERAL_CSTRING("cgroup.procs");
}
int OpenCGroupProcs()
{
return open(CGroupProcsFilename().get(), O_WRONLY);
}
};
/**
* Try to create the cgroup for the given PriorityClass, if it doesn't already
* exist. This essentially implements mkdir -p; that is, we create parent
* cgroups as necessary. The group parameters are also set according to
* the corresponding preferences.
*
* @param aGroup The name of the group.
* @return true if we successfully created the cgroup, or if it already
* exists. Otherwise, return false.
*/
static bool
EnsureCGroupExists(const nsACString &aGroup)
{
NS_NAMED_LITERAL_CSTRING(kDevCpuCtl, "/dev/cpuctl/");
NS_NAMED_LITERAL_CSTRING(kSlash, "/");
nsAutoCString prefPrefix("hal.processPriorityManager.gonk.cgroups.");
/* If cgroup is not empty, append the cgroup name and a dot to obtain the
* group specific preferences. */
if (!aGroup.IsEmpty()) {
prefPrefix += aGroup + NS_LITERAL_CSTRING(".");
}
nsAutoCString cpuSharesPref(prefPrefix + NS_LITERAL_CSTRING("cpu_shares"));
int cpuShares = Preferences::GetInt(cpuSharesPref.get());
nsAutoCString cpuNotifyOnMigratePref(prefPrefix
+ NS_LITERAL_CSTRING("cpu_notify_on_migrate"));
int cpuNotifyOnMigrate = Preferences::GetInt(cpuNotifyOnMigratePref.get());
// Create mCGroup and its parent directories, as necessary.
nsCString cgroupIter = aGroup + kSlash;
int32_t offset = 0;
while ((offset = cgroupIter.FindChar('/', offset)) != -1) {
nsAutoCString path = kDevCpuCtl + Substring(cgroupIter, 0, offset);
int rv = mkdir(path.get(), 0744);
if (rv == -1 && errno != EEXIST) {
HAL_LOG("Could not create the %s control group.", path.get());
return false;
}
offset++;
}
nsAutoCString pathPrefix(kDevCpuCtl + aGroup + kSlash);
nsAutoCString cpuSharesPath(pathPrefix + NS_LITERAL_CSTRING("cpu.shares"));
if (cpuShares && !WriteToFile(cpuSharesPath.get(),
nsPrintfCString("%d", cpuShares).get())) {
HAL_LOG("Could not set the cpu share for group %s", cpuSharesPath.get());
return false;
}
nsAutoCString notifyOnMigratePath(pathPrefix
+ NS_LITERAL_CSTRING("cpu.notify_on_migrate"));
if (!WriteToFile(notifyOnMigratePath.get(),
nsPrintfCString("%d", cpuNotifyOnMigrate).get())) {
HAL_LOG("Could not set the cpu migration notification flag for group %s",
notifyOnMigratePath.get());
return false;
}
return true;
}
PriorityClass::PriorityClass(ProcessPriority aPriority)
: mPriority(aPriority)
, mOomScoreAdj(0)
, mKillUnderKB(0)
, mCGroupProcsFd(-1)
{
DebugOnly<nsresult> rv;
rv = Preferences::GetInt(PriorityPrefName("OomScoreAdjust").get(),
&mOomScoreAdj);
MOZ_ASSERT(NS_SUCCEEDED(rv), "Missing oom_score_adj preference");
rv = Preferences::GetInt(PriorityPrefName("KillUnderKB").get(),
&mKillUnderKB);
rv = Preferences::GetCString(PriorityPrefName("cgroup").get(), &mGroup);
MOZ_ASSERT(NS_SUCCEEDED(rv), "Missing control group preference");
if (EnsureCGroupExists(mGroup)) {
mCGroupProcsFd = OpenCGroupProcs();
}
}
PriorityClass::~PriorityClass()
{
close(mCGroupProcsFd);
}
PriorityClass::PriorityClass(const PriorityClass& aOther)
: mPriority(aOther.mPriority)
, mOomScoreAdj(aOther.mOomScoreAdj)
, mKillUnderKB(aOther.mKillUnderKB)
, mGroup(aOther.mGroup)
{
mCGroupProcsFd = OpenCGroupProcs();
}
PriorityClass& PriorityClass::operator=(const PriorityClass& aOther)
{
mPriority = aOther.mPriority;
mOomScoreAdj = aOther.mOomScoreAdj;
mKillUnderKB = aOther.mKillUnderKB;
mGroup = aOther.mGroup;
mCGroupProcsFd = OpenCGroupProcs();
return *this;
}
void PriorityClass::AddProcess(int aPid)
{
if (mCGroupProcsFd < 0) {
return;
}
nsPrintfCString str("%d", aPid);
if (write(mCGroupProcsFd, str.get(), strlen(str.get())) < 0) {
HAL_ERR("Couldn't add PID %d to the %s control group", aPid, mGroup.get());
}
}
/**
* Get the PriorityClass associated with the given ProcessPriority.
*
* If you pass an invalid ProcessPriority value, we return null.
*
* The pointers returned here are owned by GetPriorityClass (don't free them
* yourself). They are guaranteed to stick around until shutdown.
*/
PriorityClass*
GetPriorityClass(ProcessPriority aPriority)
{
static StaticAutoPtr<nsTArray<PriorityClass>> priorityClasses;
// Initialize priorityClasses if this is the first time we're running this
// method.
if (!priorityClasses) {
priorityClasses = new nsTArray<PriorityClass>();
ClearOnShutdown(&priorityClasses);
for (int32_t i = 0; i < NUM_PROCESS_PRIORITY; i++) {
priorityClasses->AppendElement(PriorityClass(ProcessPriority(i)));
}
}
if (aPriority < 0 ||
static_cast<uint32_t>(aPriority) >= priorityClasses->Length()) {
return nullptr;
}
return &(*priorityClasses)[aPriority];
}
static void
EnsureKernelLowMemKillerParamsSet()
{
@ -1332,21 +1589,12 @@ EnsureKernelLowMemKillerParamsSet()
// The system doesn't function correctly if we're missing these prefs, so
// crash loudly.
ProcessPriority priority = static_cast<ProcessPriority>(i);
PriorityClass* pc = GetPriorityClass(static_cast<ProcessPriority>(i));
int32_t oomScoreAdj;
if (!NS_SUCCEEDED(Preferences::GetInt(
nsPrintfCString("hal.processPriorityManager.gonk.%s.OomScoreAdjust",
ProcessPriorityToString(priority)).get(),
&oomScoreAdj))) {
MOZ_CRASH();
}
int32_t oomScoreAdj = pc->OomScoreAdj();
int32_t killUnderKB = pc->KillUnderKB();
int32_t killUnderKB;
if (!NS_SUCCEEDED(Preferences::GetInt(
nsPrintfCString("hal.processPriorityManager.gonk.%s.KillUnderKB",
ProcessPriorityToString(priority)).get(),
&killUnderKB))) {
if (killUnderKB == 0) {
// ProcessPriority values like PROCESS_PRIORITY_FOREGROUND_KEYBOARD,
// which has only OomScoreAdjust but lacks KillUnderMB value, will not
// create new LMK parameters.
@ -1377,7 +1625,8 @@ EnsureKernelLowMemKillerParamsSet()
minfreeParams.Cut(minfreeParams.Length() - 1, 1);
if (!adjParams.IsEmpty() && !minfreeParams.IsEmpty()) {
WriteToFile("/sys/module/lowmemorykiller/parameters/adj", adjParams.get());
WriteToFile("/sys/module/lowmemorykiller/parameters/minfree", minfreeParams.get());
WriteToFile("/sys/module/lowmemorykiller/parameters/minfree",
minfreeParams.get());
}
// Set the low-memory-notification threshold.
@ -1399,148 +1648,6 @@ EnsureKernelLowMemKillerParamsSet()
}
}
static void
SetNiceForPid(int aPid, int aNice)
{
errno = 0;
int origProcPriority = getpriority(PRIO_PROCESS, aPid);
if (errno) {
HAL_LOG("Unable to get nice for pid=%d; error %d. SetNiceForPid bailing.",
aPid, errno);
return;
}
int rv = setpriority(PRIO_PROCESS, aPid, aNice);
if (rv) {
HAL_LOG("Unable to set nice for pid=%d; error %d. SetNiceForPid bailing.",
aPid, errno);
return;
}
// On Linux, setpriority(aPid) modifies the priority only of the main
// thread of that process. We have to modify the priorities of all of the
// process's threads as well, so iterate over all the threads and increase
// each of their priorites by aNice - origProcPriority (and also ensure that
// none of the tasks has a lower priority than the main thread).
//
// This is horribly racy.
DIR* tasksDir = opendir(nsPrintfCString("/proc/%d/task/", aPid).get());
if (!tasksDir) {
HAL_LOG("Unable to open /proc/%d/task. SetNiceForPid bailing.", aPid);
return;
}
// Be careful not to leak tasksDir; after this point, we must call closedir().
while (struct dirent* de = readdir(tasksDir)) {
char* endptr = nullptr;
long tidlong = strtol(de->d_name, &endptr, /* base */ 10);
if (*endptr || tidlong < 0 || tidlong > INT32_MAX || tidlong == aPid) {
// if dp->d_name was not an integer, was negative (?!) or too large, or
// was the same as aPid, we're not interested.
//
// (The |tidlong == aPid| check is very important; without it, we'll
// renice aPid twice, and the second renice will be relative to the
// priority set by the first renice.)
continue;
}
int tid = static_cast<int>(tidlong);
// Do not set the priority of threads running with a real-time policy
// as part of the bulk process adjustment. These threads need to run
// at their specified priority in order to meet timing guarantees.
int schedPolicy = sched_getscheduler(tid);
if (schedPolicy == SCHED_FIFO || schedPolicy == SCHED_RR) {
continue;
}
errno = 0;
// Get and set the task's new priority.
int origtaskpriority = getpriority(PRIO_PROCESS, tid);
if (errno) {
HAL_LOG("Unable to get nice for tid=%d (pid=%d); error %d. This isn't "
"necessarily a problem; it could be a benign race condition.",
tid, aPid, errno);
continue;
}
int newtaskpriority =
std::max(origtaskpriority - origProcPriority + aNice, aNice);
// Do not reduce priority of threads already running at priorities greater
// than normal. These threads are likely special service threads that need
// elevated priorities to process audio, display composition, etc.
if (newtaskpriority > origtaskpriority &&
origtaskpriority < ANDROID_PRIORITY_NORMAL) {
continue;
}
rv = setpriority(PRIO_PROCESS, tid, newtaskpriority);
if (rv) {
HAL_LOG("Unable to set nice for tid=%d (pid=%d); error %d. This isn't "
"necessarily a problem; it could be a benign race condition.",
tid, aPid, errno);
continue;
}
}
HAL_LOG("Changed nice for pid %d from %d to %d.",
aPid, origProcPriority, aNice);
closedir(tasksDir);
}
/*
* Used to store the nice value adjustments and oom_adj values for the various
* process priority levels.
*/
struct ProcessPriorityPrefs {
bool initialized;
int lowPriorityNice;
struct {
int nice;
int oomScoreAdj;
} priorities[NUM_PROCESS_PRIORITY];
};
/*
* Reads the preferences for the various process priority levels and sets up
* watchers so that if they're dynamically changed the change is reflected on
* the appropriate variables.
*/
void
EnsureProcessPriorityPrefs(ProcessPriorityPrefs* prefs)
{
if (prefs->initialized) {
return;
}
// Read the preferences for process priority levels
for (int i = PROCESS_PRIORITY_BACKGROUND; i < NUM_PROCESS_PRIORITY; i++) {
ProcessPriority priority = static_cast<ProcessPriority>(i);
// Read the nice values
const char* processPriorityStr = ProcessPriorityToString(priority);
nsPrintfCString niceStr("hal.processPriorityManager.gonk.%s.Nice",
processPriorityStr);
Preferences::AddIntVarCache(&prefs->priorities[i].nice, niceStr.get());
// Read the oom_adj scores
nsPrintfCString oomStr("hal.processPriorityManager.gonk.%s.OomScoreAdjust",
processPriorityStr);
Preferences::AddIntVarCache(&prefs->priorities[i].oomScoreAdj,
oomStr.get());
}
Preferences::AddIntVarCache(&prefs->lowPriorityNice,
"hal.processPriorityManager.gonk.LowCPUNice");
prefs->initialized = true;
}
void
SetProcessPriority(int aPid,
ProcessPriority aPriority,
@ -1559,49 +1666,23 @@ SetProcessPriority(int aPid,
// SetProcessPriority being called early in startup.
EnsureKernelLowMemKillerParamsSet();
static ProcessPriorityPrefs prefs = { 0 };
EnsureProcessPriorityPrefs(&prefs);
PriorityClass* pc = GetPriorityClass(aPriority);
int oomScoreAdj = prefs.priorities[aPriority].oomScoreAdj;
int oomScoreAdj = pc->OomScoreAdj();
RoundOomScoreAdjUpWithBackroundLRU(oomScoreAdj, aBackgroundLRU);
int clampedOomScoreAdj = clamped<int>(oomScoreAdj, OOM_SCORE_ADJ_MIN,
OOM_SCORE_ADJ_MAX);
if (clampedOomScoreAdj != oomScoreAdj) {
HAL_LOG("Clamping OOM adjustment for pid %d to %d", aPid,
clampedOomScoreAdj);
} else {
HAL_LOG("Setting OOM adjustment for pid %d to %d", aPid,
clampedOomScoreAdj);
}
// We try the newer interface first, and fall back to the older interface
// on failure.
if (!WriteToFile(nsPrintfCString("/proc/%d/oom_score_adj", aPid).get(),
nsPrintfCString("%d", clampedOomScoreAdj).get()))
nsPrintfCString("%d", oomScoreAdj).get()))
{
int oomAdj = OomAdjOfOomScoreAdj(clampedOomScoreAdj);
WriteToFile(nsPrintfCString("/proc/%d/oom_adj", aPid).get(),
nsPrintfCString("%d", oomAdj).get());
nsPrintfCString("%d", OomAdjOfOomScoreAdj(oomScoreAdj)).get());
}
int nice = 0;
if (aCPUPriority == PROCESS_CPU_PRIORITY_NORMAL) {
nice = prefs.priorities[aPriority].nice;
} else if (aCPUPriority == PROCESS_CPU_PRIORITY_LOW) {
nice = prefs.lowPriorityNice;
} else {
HAL_ERR("Unknown aCPUPriority value %d", aCPUPriority);
MOZ_ASSERT(false);
return;
}
HAL_LOG("Setting nice for pid %d to %d", aPid, nice);
SetNiceForPid(aPid, nice);
HAL_LOG("Assigning pid %d to cgroup %s", aPid, pc->CGroup().get());
pc->AddProcess(aPid);
}
static bool