* [PATCH] sched/core: fix incorrect parameter burst in cpu_max_write()
@ 2024-04-24 13:24 Cheng Yu
2024-05-02 8:57 ` Vincent Guittot
2024-05-17 8:06 ` [tip: sched/urgent] sched/core: Fix incorrect initialization of the 'burst' parameter " tip-bot2 for Cheng Yu
0 siblings, 2 replies; 3+ messages in thread
From: Cheng Yu @ 2024-04-24 13:24 UTC (permalink / raw
To: mingo, peterz, juri.lelli, vincent.guittot, dietmar.eggemann,
rostedt, bsegall, mgorman, bristot, vschneid, changhuaixin,
shanpeic, dtcccc, tj, linux-kernel
Cc: zhangqiao22, judy.chenhui, yusongping, serein.chengyu
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] sched/core: fix incorrect parameter burst in cpu_max_write()
2024-04-24 13:24 [PATCH] sched/core: fix incorrect parameter burst in cpu_max_write() Cheng Yu
@ 2024-05-02 8:57 ` Vincent Guittot
2024-05-17 8:06 ` [tip: sched/urgent] sched/core: Fix incorrect initialization of the 'burst' parameter " tip-bot2 for Cheng Yu
1 sibling, 0 replies; 3+ messages in thread
From: Vincent Guittot @ 2024-05-02 8:57 UTC (permalink / raw
To: Cheng Yu
Cc: mingo, peterz, juri.lelli, dietmar.eggemann, rostedt, bsegall,
mgorman, bristot, vschneid, changhuaixin, shanpeic, dtcccc, tj,
linux-kernel, zhangqiao22, judy.chenhui, yusongping
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
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* [tip: sched/urgent] sched/core: Fix incorrect initialization of the 'burst' parameter in cpu_max_write()
2024-04-24 13:24 [PATCH] sched/core: fix incorrect parameter burst in cpu_max_write() Cheng Yu
2024-05-02 8:57 ` Vincent Guittot
@ 2024-05-17 8:06 ` tip-bot2 for Cheng Yu
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot2 for Cheng Yu @ 2024-05-17 8:06 UTC (permalink / raw
To: linux-tip-commits
Cc: Qixin Liao, Cheng Yu, Zhang Qiao, Ingo Molnar, Vincent Guittot,
x86, linux-kernel
The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: 49217ea147df7647cb89161b805c797487783fc0
Gitweb: https://git.kernel.org/tip/49217ea147df7647cb89161b805c797487783fc0
Author: Cheng Yu <serein.chengyu@huawei.com>
AuthorDate: Wed, 24 Apr 2024 21:24:38 +08:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Fri, 17 May 2024 09:53:54 +02:00
sched/core: Fix incorrect initialization of the 'burst' parameter in cpu_max_write()
In the cgroup v2 CPU subsystem, assuming we have a
cgroup named 'test', and 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 find 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, get the burst value directly from tg->cfs_bandwidth.burst.
Fixes: f4183717b370 ("sched/fair: Introduce the burstable CFS controller")
Reported-by: Qixin Liao <liaoqixin@huawei.com>
Signed-off-by: Cheng Yu <serein.chengyu@huawei.com>
Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240424132438.514720-1-serein.chengyu@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 1a91438..f88f505 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;
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2024-04-24 13:24 [PATCH] sched/core: fix incorrect parameter burst in cpu_max_write() Cheng Yu
2024-05-02 8:57 ` Vincent Guittot
2024-05-17 8:06 ` [tip: sched/urgent] sched/core: Fix incorrect initialization of the 'burst' parameter " tip-bot2 for Cheng Yu
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