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Merge branch 'for-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

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Pull cgroup updates from Tejun Heo:
 "Just two patches: one to add system-level cpu.stat to the root cgroup
  for convenience and a trivial comment update"

* 'for-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: add cpu.stat file to root cgroup
  cgroup: Remove stale comments
This commit is contained in:
Linus Torvalds 2020-06-06 09:59:34 -07:00
commit 4a7e89c5ec
3 changed files with 54 additions and 20 deletions
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6
Documentation/admin-guide/cgroup-v2.rst
View File

@ -714,9 +714,7 @@ Conventions
- Settings for a single feature should be contained in a single file.
- The root cgroup should be exempt from resource control and thus
shouldn't have resource control interface files. Also,
informational files on the root cgroup which end up showing global
information available elsewhere shouldn't exist.
shouldn't have resource control interface files.
- The default time unit is microseconds. If a different unit is ever
used, an explicit unit suffix must be present.
@ -985,7 +983,7 @@ CPU Interface Files
All time durations are in microseconds.
cpu.stat
A read-only flat-keyed file which exists on non-root cgroups.
A read-only flat-keyed file.
This file exists whether the controller is enabled or not.
It always reports the following three stats:

10
kernel/cgroup/cgroup.c
View File

@ -153,11 +153,7 @@ static struct static_key_true *cgroup_subsys_on_dfl_key[] = {
static DEFINE_PER_CPU(struct cgroup_rstat_cpu, cgrp_dfl_root_rstat_cpu);
/*
* The default hierarchy, reserved for the subsystems that are otherwise
* unattached - it never has more than a single cgroup, and all tasks are
* part of that cgroup.
*/
/* the default hierarchy */
struct cgroup_root cgrp_dfl_root = { .cgrp.rstat_cpu = &cgrp_dfl_root_rstat_cpu };
EXPORT_SYMBOL_GPL(cgrp_dfl_root);
@ -251,9 +247,6 @@ bool cgroup_ssid_enabled(int ssid)
* cases where a subsystem should behave differnetly depending on the
* interface version.
*
* The set of behaviors which change on the default hierarchy are still
* being determined and the mount option is prefixed with __DEVEL__.
*
* List of changed behaviors:
*
* - Mount options "noprefix", "xattr", "clone_children", "release_agent"
@ -4881,7 +4874,6 @@ static struct cftype cgroup_base_files[] = {
},
{
.name = "cpu.stat",
.flags = CFTYPE_NOT_ON_ROOT,
.seq_show = cpu_stat_show,
},
#ifdef CONFIG_PSI

58
kernel/cgroup/rstat.c
View File

@ -389,18 +389,62 @@ void __cgroup_account_cputime_field(struct cgroup *cgrp,
cgroup_base_stat_cputime_account_end(cgrp, rstatc);
}
/*
* compute the cputime for the root cgroup by getting the per cpu data
* at a global level, then categorizing the fields in a manner consistent
* with how it is done by __cgroup_account_cputime_field for each bit of
* cpu time attributed to a cgroup.
*/
static void root_cgroup_cputime(struct task_cputime *cputime)
{
int i;
cputime->stime = 0;
cputime->utime = 0;
cputime->sum_exec_runtime = 0;
for_each_possible_cpu(i) {
struct kernel_cpustat kcpustat;
u64 *cpustat = kcpustat.cpustat;
u64 user = 0;
u64 sys = 0;
kcpustat_cpu_fetch(&kcpustat, i);
user += cpustat[CPUTIME_USER];
user += cpustat[CPUTIME_NICE];
cputime->utime += user;
sys += cpustat[CPUTIME_SYSTEM];
sys += cpustat[CPUTIME_IRQ];
sys += cpustat[CPUTIME_SOFTIRQ];
cputime->stime += sys;
cputime->sum_exec_runtime += user;
cputime->sum_exec_runtime += sys;
cputime->sum_exec_runtime += cpustat[CPUTIME_STEAL];
cputime->sum_exec_runtime += cpustat[CPUTIME_GUEST];
cputime->sum_exec_runtime += cpustat[CPUTIME_GUEST_NICE];
}
}
void cgroup_base_stat_cputime_show(struct seq_file *seq)
{
struct cgroup *cgrp = seq_css(seq)->cgroup;
u64 usage, utime, stime;
struct task_cputime cputime;
if (!cgroup_parent(cgrp))
return;
cgroup_rstat_flush_hold(cgrp);
usage = cgrp->bstat.cputime.sum_exec_runtime;
cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime, &utime, &stime);
cgroup_rstat_flush_release();
if (cgroup_parent(cgrp)) {
cgroup_rstat_flush_hold(cgrp);
usage = cgrp->bstat.cputime.sum_exec_runtime;
cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime,
&utime, &stime);
cgroup_rstat_flush_release();
} else {
root_cgroup_cputime(&cputime);
usage = cputime.sum_exec_runtime;
utime = cputime.utime;
stime = cputime.stime;
}
do_div(usage, NSEC_PER_USEC);
do_div(utime, NSEC_PER_USEC);