[PATCH v5 1/9] kernel/sched: introduce vcpu preempted check interface
flat view
STALE3658d
SUPERSEDED: 2 (1M)
From: Pan Xinhui <hidden>
Date: 2016-10-20 17:31:27
Also in:
kvm, linux-s390, lkml, virtualization
Subsystem:
scheduler, the rest · Maintainers:
Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
Status: Superseded by v7 (posted 2016-11-02). [go to v7]
Revision v5 (7 revisions archived); 2 review trailers.
Revisions (7)
- v1 re-posted go to this post
- v2 [diff against previous]
- v3 [diff against previous] re-posted go to this post
- v4 [diff against previous]
- v5 current [diff against previous]
- v6 [diff against previous] re-posted go to this post re-posted go to this post
- v7 [diff against previous] re-posted go to this post
This patch support to fix lock holder preemption issue. For kernel users, we could use bool vcpu_is_preempted(int cpu) to detech if one vcpu is preempted or not. The default implementation is a macro defined by false. So compiler can wrap it out if arch dose not support such vcpu pteempted check. Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Pan Xinhui <redacted> Acked-by: Christian Borntraeger <redacted> Tested-by: Juergen Gross <jgross@suse.com> --- include/linux/sched.h | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 348f51b..44c1ce7 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h@@ -3506,6 +3506,18 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu) #endif /* CONFIG_SMP */ +/* + * In order to deal with a various lock holder preemption issues provide an + * interface to see if a vCPU is currently running or not. + * + * This allows us to terminate optimistic spin loops and block, analogous to + * the native optimistic spin heuristic of testing if the lock owner task is + * running or not. + */ +#ifndef vcpu_is_preempted +#define vcpu_is_preempted(cpu) false +#endif + extern long sched_setaffinity(pid_t pid, const struct cpumask *new_mask); extern long sched_getaffinity(pid_t pid, struct cpumask *mask);
--
2.4.11