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pkg/sysinfo: omit Getpid call in numCPU

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The man page for sched_setaffinity(2) states the following about the pid
argument [1]:

> If pid is zero, then the mask of the calling thread is returned.

Thus the additional call to unix.Getpid can be omitted and pid = 0
passed to unix.SchedGetaffinity.

[1] https://man7.org/linux/man-pages/man2/sched_setaffinity.2.html#DESCRIPTION

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
This commit is contained in:
Tobias Klauser 2023-04-25 10:05:11 +02:00
parent 9ff00e35f8
commit 4ec063fade
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GPG key ID: 6F5040074CCC0D04
1 changed files with 2 additions and 8 deletions
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10
pkg/sysinfo/numcpu_linux.go
View file

@ -1,23 +1,17 @@
package sysinfo // import "github.com/docker/docker/pkg/sysinfo"
import (
"golang.org/x/sys/unix"
)
import "golang.org/x/sys/unix"
// numCPU queries the system for the count of threads available
// for use to this process.
//
// Issues two syscalls.
// Returns 0 on errors. Use |runtime.NumCPU| in that case.
func numCPU() int {
// Gets the affinity mask for a process: The very one invoking this function.
pid := unix.Getpid()
var mask unix.CPUSet
err := unix.SchedGetaffinity(pid, &mask)
err := unix.SchedGetaffinity(0, &mask)
if err != nil {
return 0
}
return mask.Count()
}