Commit-ID: d9345c65eb7930ac6755cf593ee7686f4029ccf4 Gitweb: http://git.kernel.org/tip/d9345c65eb7930ac6755cf593ee7686f4029ccf4 Author: Pan Xinhui <xinhui.pan@xxxxxxxxxxxxxxxxxx> AuthorDate: Wed, 2 Nov 2016 05:08:28 -0400 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Tue, 22 Nov 2016 12:48:05 +0100 sched/core: Introduce the vcpu_is_preempted(cpu) interface This patch is the first step to add support to improve lock holder preemption beaviour. vcpu_is_preempted(cpu) does the obvious thing: it tells us whether a vCPU is preempted or not. Defaults to false on architectures that don't support it. Suggested-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Tested-by: Juergen Gross <jgross@xxxxxxxx> Signed-off-by: Pan Xinhui <xinhui.pan@xxxxxxxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> [ Translated the changelog to English. ] Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: David.Laight@xxxxxxxxxx Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: benh@xxxxxxxxxxxxxxxxxxx Cc: boqun.feng@xxxxxxxxx Cc: bsingharora@xxxxxxxxx Cc: dave@xxxxxxxxxxxx Cc: kernellwp@xxxxxxxxx Cc: konrad.wilk@xxxxxxxxxx Cc: linuxppc-dev@xxxxxxxxxxxxxxxx Cc: mpe@xxxxxxxxxxxxxx Cc: paulmck@xxxxxxxxxxxxxxxxxx Cc: paulus@xxxxxxxxx Cc: rkrcmar@xxxxxxxxxx Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx Cc: will.deacon@xxxxxxx Cc: xen-devel-request@xxxxxxxxxxxxxxxxxxxx Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/1478077718-37424-2-git-send-email-xinhui.pan@xxxxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- include/linux/sched.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/include/linux/sched.h b/include/linux/sched.h index dc37cbe..37261af 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -3510,6 +3510,18 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu) #endif /* CONFIG_SMP */ +/* + * In order to reduce various lock holder preemption latencies 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); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|