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authorTejun Heo <tj@kernel.org>2015-12-03 10:18:21 -0500
committerTejun Heo <tj@kernel.org>2015-12-03 10:18:21 -0500
commit67cde9c4938945b9510730c64e68d2f1dd7bc0aa (patch)
tree208946c2b33e3eeaa8e7f7d0eedc0a9c0401b4bd /kernel
parent1f7dd3e5a6e4f093017fff12232572ee1aa4639b (diff)
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cgroup_pids: don't account for the root cgroup
Because accounting resources for the root cgroup sometimes incurs measureable overhead for workloads which don't care about cgroup and often ends up calculating a number which is available elsewhere in a slightly different form, cgroup is not in the business of providing system-wide statistics. The pids controller which was introduced recently was exposing "pids.current" at the root. This patch disable accounting for root cgroup and removes the file from the root directory. While this is a userland visible behavior change, pids has been available only in one version and was badly broken there, so I don't think this will be noticeable. If it turns out to be a problem, we can reinstate it for v1 hierarchies. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Aleksa Sarai <cyphar@cyphar.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup_pids.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/cgroup_pids.c b/kernel/cgroup_pids.c
index 8e27fc5dbb20..b50d5a167fda 100644
--- a/kernel/cgroup_pids.c
+++ b/kernel/cgroup_pids.c
@@ -106,7 +106,7 @@ static void pids_uncharge(struct pids_cgroup *pids, int num)
{
struct pids_cgroup *p;
- for (p = pids; p; p = parent_pids(p))
+ for (p = pids; parent_pids(p); p = parent_pids(p))
pids_cancel(p, num);
}
@@ -123,7 +123,7 @@ static void pids_charge(struct pids_cgroup *pids, int num)
{
struct pids_cgroup *p;
- for (p = pids; p; p = parent_pids(p))
+ for (p = pids; parent_pids(p); p = parent_pids(p))
atomic64_add(num, &p->counter);
}
@@ -140,7 +140,7 @@ static int pids_try_charge(struct pids_cgroup *pids, int num)
{
struct pids_cgroup *p, *q;
- for (p = pids; p; p = parent_pids(p)) {
+ for (p = pids; parent_pids(p); p = parent_pids(p)) {
int64_t new = atomic64_add_return(num, &p->counter);
/*
@@ -298,6 +298,7 @@ static struct cftype pids_files[] = {
{
.name = "current",
.read_s64 = pids_current_read,
+ .flags = CFTYPE_NOT_ON_ROOT,
},
{ } /* terminate */
};