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| author | Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> | 2016-11-02 05:08:28 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-11-22 12:48:05 +0100 |
| commit | d9345c65eb7930ac6755cf593ee7686f4029ccf4 (patch) | |
| tree | 997e488123a15a9725bd6c6ee454500f4b63a66d /include/linux/sched.h | |
| parent | 02cb689b2c102178c83e763e4f34b3efe7f969e2 (diff) | |
| download | op-kernel-dev-d9345c65eb7930ac6755cf593ee7686f4029ccf4.zip op-kernel-dev-d9345c65eb7930ac6755cf593ee7686f4029ccf4.tar.gz | |
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@infradead.org>
Tested-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[ Translated the changelog to English. ]
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: benh@kernel.crashing.org
Cc: boqun.feng@gmail.com
Cc: bsingharora@gmail.com
Cc: dave@stgolabs.net
Cc: kernellwp@gmail.com
Cc: konrad.wilk@oracle.com
Cc: linuxppc-dev@lists.ozlabs.org
Cc: mpe@ellerman.id.au
Cc: paulmck@linux.vnet.ibm.com
Cc: paulus@samba.org
Cc: rkrcmar@redhat.com
Cc: virtualization@lists.linux-foundation.org
Cc: will.deacon@arm.com
Cc: xen-devel-request@lists.xenproject.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1478077718-37424-2-git-send-email-xinhui.pan@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/sched.h')
| -rw-r--r-- | include/linux/sched.h | 12 |
1 files changed, 12 insertions, 0 deletions
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); |
