bool MemoryPressureHandler::tryEnsureEventFD()
{
// If the env var to use the poll method based on meminfo is set, this method overrides anything else.
if (m_eventFD != -1 && defaultPollMaximumProcessMemory(s_pollMaximumProcessMemoryCriticalLimit, s_pollMaximumProcessMemoryNonCriticalLimit)) {
m_eventFD = -1;
return true;
}
if (m_eventFD)
return true;
auto setupCgroups = [this]() -> bool {
int fd = eventfd(0, EFD_CLOEXEC);
if (fd == -1) {
LOG(MemoryPressure, "eventfd() failed: %m");
return false;
}
m_eventFD = fd;
fd = open(s_cgroupMemoryPressureLevel, O_CLOEXEC | O_RDONLY);
if (fd == -1) {
logErrorAndCloseFDs("Failed to open memory.pressure_level");
return false;
}
m_pressureLevelFD = fd;
fd = open(s_cgroupEventControl, O_CLOEXEC | O_WRONLY);
if (fd == -1) {
logErrorAndCloseFDs("Failed to open cgroup.event_control");
return false;
}
char line[128] = {0, };
if (snprintf(line, sizeof(line), "%d %d low", m_eventFD.value(), m_pressureLevelFD.value()) < 0
|| write(fd, line, strlen(line) + 1) < 0) {
logErrorAndCloseFDs("Failed to write cgroup.event_control");
close(fd);
return false;
}
return true;
};
if (setupCgroups())
return true;
return false;
}
void MemoryPressureHandler::install()
{
if (m_installed)
return;
m_eventFD = eventfd(0, EFD_CLOEXEC);
if (m_eventFD == -1) {
LOG(MemoryPressure, "eventfd() failed: %m");
return;
}
m_pressureLevelFD = open(s_cgroupMemoryPressureLevel, O_CLOEXEC | O_RDONLY);
if (m_pressureLevelFD == -1) {
logErrorAndCloseFDs("Failed to open memory.pressure_level");
return;
}
int fd = open(s_cgroupEventControl, O_CLOEXEC | O_WRONLY);
if (fd == -1) {
logErrorAndCloseFDs("Failed to open cgroup.event_control");
return;
}
char line[128] = {0, };
if (snprintf(line, sizeof(line), "%d %d low", m_eventFD, m_pressureLevelFD) < 0
|| write(fd, line, strlen(line) + 1) < 0) {
logErrorAndCloseFDs("Failed to write cgroup.event_control");
close(fd);
return;
}
close(fd);
m_threadID = createThread(waitForMemoryPressureEvent, this, "WebCore: MemoryPressureHandler");
if (!m_threadID) {
logErrorAndCloseFDs("Failed to create a thread for MemoryPressureHandler");
return;
}
if (ReliefLogger::loggingEnabled() && isUnderMemoryPressure())
LOG(MemoryPressure, "System is no longer under memory pressure.");
setUnderMemoryPressure(false);
m_installed = true;
}
void MemoryPressureHandler::uninstall()
{
if (!m_installed)
return;
if (m_threadID) {
detachThread(m_threadID);
m_threadID = 0;
}
logErrorAndCloseFDs(nullptr);
m_installed = false;
}
