diff options
| author | Tejun Heo <tj@kernel.org> | 2024-11-05 11:49:04 -1000 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2024-11-08 10:42:22 -1000 |
| commit | e32c260195e6ff72940ab7826e38e0a0066fc58f (patch) | |
| tree | 4397fbaba6a85afa05b90fb9a1c5d31c10e6e16b /include/linux/sched | |
| parent | 62dcbab8b0ef21729532600039fd514c09407092 (diff) | |
sched_ext: Enable the ops breather and eject BPF scheduler on softlockup
On 2 x Intel Sapphire Rapids machines with 224 logical CPUs, a poorly
behaving BPF scheduler can live-lock the system by making multiple CPUs bang
on the same DSQ to the point where soft-lockup detection triggers before
SCX's own watchdog can take action. It also seems possible that the machine
can be live-locked enough to prevent scx_ops_helper, which is an RT task,
from running in a timely manner.
Implement scx_softlockup() which is called when three quarters of
soft-lockup threshold has passed. The function immediately enables the ops
breather and triggers an ops error to initiate ejection of the BPF
scheduler.
The previous and this patch combined enable the kernel to reliably recover
the system from live-lock conditions that can be triggered by a poorly
behaving BPF scheduler on Intel dual socket systems.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux/sched')
| -rw-r--r-- | include/linux/sched/ext.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/sched/ext.h b/include/linux/sched/ext.h index 1ddbde64a31b..65bc0a489cd2 100644 --- a/include/linux/sched/ext.h +++ b/include/linux/sched/ext.h @@ -205,11 +205,13 @@ struct sched_ext_entity { void sched_ext_free(struct task_struct *p); void print_scx_info(const char *log_lvl, struct task_struct *p); +void scx_softlockup(u32 dur_s); #else /* !CONFIG_SCHED_CLASS_EXT */ static inline void sched_ext_free(struct task_struct *p) {} static inline void print_scx_info(const char *log_lvl, struct task_struct *p) {} +static inline void scx_softlockup(u32 dur_s) {} #endif /* CONFIG_SCHED_CLASS_EXT */ #endif /* _LINUX_SCHED_EXT_H */ |