Kernel.cpuClockTicker increments kernel.cpuClock, which tasks use as a clock to
track their CPU usage. This improves latency in the syscall path by avoid
expensive monotonic clock calls on every syscall entry/exit.
However, this timer fires every 10ms. Thus, when all tasks are idle (i.e.,
blocked or stopped), this forces a sentry wakeup every 10ms, when we may
otherwise be able to sleep until the next app-relevant event. These wakeups
cause the sentry to utilize approximately 2% CPU when the application is
otherwise idle.
Updates to clock are not strictly necessary when the app is idle, as there are
no readers of cpuClock. This commit reduces idle CPU by disabling the timer
when tasks are completely idle, and computing its effects at the next wakeup.
Rather than disabling the timer as soon as the app goes idle, we wait until the
next tick, which provides a window for short sleeps to sleep and wakeup without
doing the (relatively) expensive work of disabling and enabling the timer.
PiperOrigin-RevId: 272265822
When pipe is created, a dirent of pipe will be
created and its initial reference is set as 0.
Cause all dirent will only be destroyed when
the reference decreased to -1, so there is already
a 'initial reference' of dirent after it created.
For destroying dirent after all reference released,
the correct way is to drop the 'initial reference'
once someone hold a reference to the dirent, such
as fs.NewFile, otherwise the reference of dirent
will stay 0 all the time, and will cause memory
leak of dirent.
Except pipe, timerfd/eventfd/epoll has the same
problem
Here is a simple case to create memory leak of dirent
for pipe/timerfd/eventfd/epoll in C langange, after
run the case, pprof the runsc process, you will
find lots dirents of pipe/timerfd/eventfd/epoll not
freed:
int main(int argc, char *argv[])
{
int i;
int n;
int pipefd[2];
if (argc != 3) {
printf("Usage: %s epoll|timerfd|eventfd|pipe <iterations>\n", argv[0]);
}
n = strtol(argv[2], NULL, 10);
if (strcmp(argv[1], "epoll") == 0) {
for (i = 0; i < n; ++i)
close(epoll_create(1));
} else if (strcmp(argv[1], "timerfd") == 0) {
for (i = 0; i < n; ++i)
close(timerfd_create(CLOCK_REALTIME, 0));
} else if (strcmp(argv[1], "eventfd") == 0) {
for (i = 0; i < n; ++i)
close(eventfd(0, 0));
} else if (strcmp(argv[1], "pipe") == 0) {
for (i = 0; i < n; ++i)
if (pipe(pipefd) == 0) {
close(pipefd[0]);
close(pipefd[1]);
}
}
printf("%s %s test finished\r\n",argv[1],argv[2]);
return 0;
}
Change-Id: Ia1b8a1fb9142edb00c040e44ec644d007f81f5d2
PiperOrigin-RevId: 251531096
This does not actually implement an efficient splice or sendfile. Rather, it
adds a generic plumbing to the file internals so that this can be added. All
file implementations use the stub fileutil.NoSplice implementation, which
causes sendfile and splice to fall back to an internal copy.
A basic splice system call interface is added, along with a test.
PiperOrigin-RevId: 249335960
Change-Id: Ic5568be2af0a505c19e7aec66d5af2480ab0939b
Based on the guidelines at
https://opensource.google.com/docs/releasing/authors/.
1. $ rg -l "Google LLC" | xargs sed -i 's/Google LLC.*/The gVisor Authors./'
2. Manual fixup of "Google Inc" references.
3. Add AUTHORS file. Authors may request to be added to this file.
4. Point netstack AUTHORS to gVisor AUTHORS. Drop CONTRIBUTORS.
Fixes#209
PiperOrigin-RevId: 245823212
Change-Id: I64530b24ad021a7d683137459cafc510f5ee1de9
Nothing reads them and they can simply get stale.
Generated with:
$ sed -i "s/licenses(\(.*\)).*/licenses(\1)/" **/BUILD
PiperOrigin-RevId: 231818945
Change-Id: Ibc3f9838546b7e94f13f217060d31f4ada9d4bf0
More helper structs have been added to the fsutil package to make it easier to
implement fs.InodeOperations and fs.FileOperations.
PiperOrigin-RevId: 229305982
Change-Id: Ib6f8d3862f4216745116857913dbfa351530223b
We have been unnecessarily creating too many savable types implicitly.
PiperOrigin-RevId: 206334201
Change-Id: Idc5a3a14bfb7ee125c4f2bb2b1c53164e46f29a8
Kevin Krakauer
Michael Pratt
Ian Gudger
Adin Scannell
Yong He
Jamie Liu
Nicolas Lacasse
Zhaozhong Ni
Googler