kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
In the cgroup v2 cpu subsystem, assuming we have a
cgroup named test, we set cpu.max and cpu.max.burst:
# echo 1000000 > /sys/fs/cgroup/test/cpu.max
# echo 1000000 > /sys/fs/cgroup/test/cpu.max.burst
then we check cpu.max and cpu.max.burst:
# cat /sys/fs/cgroup/test/cpu.max
1000000 100000
# cat /sys/fs/cgroup/test/cpu.max.burst
1000000
Next we set cpu.max again and check cpu.max and
cpu.max.burst:
# echo 2000000 > /sys/fs/cgroup/test/cpu.max
# cat /sys/fs/cgroup/test/cpu.max
2000000 100000
# cat /sys/fs/cgroup/test/cpu.max.burst
1000
we found that the cpu.max.burst value changed unexpectedly.
In cpu_max_write(), the unit of the burst value returned
by tg_get_cfs_burst() is microseconds, while in cpu_max_write(),
the burst unit used for calculation should be nanoseconds,
which leads to the bug.
To fix it, we get the burst value directly from
tg->cfs_bandwidth.burst.
Reported-by: Qixin Liao <liaoqixin@huawei.com>
Fixes: f4183717b370 ("sched/fair: Introduce the burstable CFS controller")
Signed-off-by: Cheng Yu <serein.chengyu@huawei.com>
Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com>
---
kernel/sched/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7019a40457a6..d211d40a2edc 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -11402,7 +11402,7 @@ static ssize_t cpu_max_write(struct kernfs_open_file *of,
{
struct task_group *tg = css_tg(of_css(of));
u64 period = tg_get_cfs_period(tg);
- u64 burst = tg_get_cfs_burst(tg);
+ u64 burst = tg->cfs_bandwidth.burst;
u64 quota;
int ret;
--
2.25.1
On Wed, 24 Apr 2024 at 15:29, Cheng Yu <serein.chengyu@huawei.com> wrote: > > In the cgroup v2 cpu subsystem, assuming we have a > cgroup named test, we set cpu.max and cpu.max.burst: > # echo 1000000 > /sys/fs/cgroup/test/cpu.max > # echo 1000000 > /sys/fs/cgroup/test/cpu.max.burst > then we check cpu.max and cpu.max.burst: > # cat /sys/fs/cgroup/test/cpu.max > 1000000 100000 > # cat /sys/fs/cgroup/test/cpu.max.burst > 1000000 > > Next we set cpu.max again and check cpu.max and > cpu.max.burst: > # echo 2000000 > /sys/fs/cgroup/test/cpu.max > # cat /sys/fs/cgroup/test/cpu.max > 2000000 100000 > # cat /sys/fs/cgroup/test/cpu.max.burst > 1000 > we found that the cpu.max.burst value changed unexpectedly. > > In cpu_max_write(), the unit of the burst value returned > by tg_get_cfs_burst() is microseconds, while in cpu_max_write(), > the burst unit used for calculation should be nanoseconds, > which leads to the bug. > > To fix it, we get the burst value directly from > tg->cfs_bandwidth.burst. > > Reported-by: Qixin Liao <liaoqixin@huawei.com> > Fixes: f4183717b370 ("sched/fair: Introduce the burstable CFS controller") > Signed-off-by: Cheng Yu <serein.chengyu@huawei.com> > Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Tested-by: Vincent Guittot <vincent.guittot@linaro.org> > --- > kernel/sched/core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 7019a40457a6..d211d40a2edc 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -11402,7 +11402,7 @@ static ssize_t cpu_max_write(struct kernfs_open_file *of, > { > struct task_group *tg = css_tg(of_css(of)); > u64 period = tg_get_cfs_period(tg); > - u64 burst = tg_get_cfs_burst(tg); > + u64 burst = tg->cfs_bandwidth.burst; > u64 quota; > int ret; > > -- > 2.25.1 > >
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