* [PATCH v2] locking/pvqspinlock: Wait early if vCPU is preempted
@ 2017-01-10 7:56 Pan Xinhui
2017-01-12 10:06 ` [tip:locking/core] locking/pvqspinlock: Don't wait " tip-bot for Pan Xinhui
0 siblings, 1 reply; 2+ messages in thread
From: Pan Xinhui @ 2017-01-10 7:56 UTC (permalink / raw)
To: linux-kernel; +Cc: mingo, peterz, longman, Pan Xinhui
If prev node is not in runnig state or its vCPU is preempted, we can give
up our vCPU slices ASAP in pv_wait_node. After commit d9345c65eb79
("sched/core: Introduce the vcpu_is_preempted(cpu) interface") kernel
has knowledge of one vCPU is running or not.
Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
---
v2:
rewrite the commit message as Ingo pointed out the mistake.
---
kernel/locking/qspinlock_paravirt.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
index e3b5520..48648dc 100644
--- a/kernel/locking/qspinlock_paravirt.h
+++ b/kernel/locking/qspinlock_paravirt.h
@@ -263,7 +263,8 @@ pv_wait_early(struct pv_node *prev, int loop)
if ((loop & PV_PREV_CHECK_MASK) != 0)
return false;
- return READ_ONCE(prev->state) != vcpu_running;
+ return READ_ONCE(prev->state) != vcpu_running ||
+ vcpu_is_preempted(prev->cpu);
}
/*
--
2.4.11
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [tip:locking/core] locking/pvqspinlock: Don't wait if vCPU is preempted
2017-01-10 7:56 [PATCH v2] locking/pvqspinlock: Wait early if vCPU is preempted Pan Xinhui
@ 2017-01-12 10:06 ` tip-bot for Pan Xinhui
0 siblings, 0 replies; 2+ messages in thread
From: tip-bot for Pan Xinhui @ 2017-01-12 10:06 UTC (permalink / raw)
To: linux-tip-commits
Cc: hpa, xinhui.pan, torvalds, peterz, linux-kernel, mingo, tglx
Commit-ID: 75437bb304b20a2b350b9a8e9f9238d5e24e12ba
Gitweb: http://git.kernel.org/tip/75437bb304b20a2b350b9a8e9f9238d5e24e12ba
Author: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
AuthorDate: Tue, 10 Jan 2017 02:56:46 -0500
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 12 Jan 2017 09:35:57 +0100
locking/pvqspinlock: Don't wait if vCPU is preempted
If prev node is not in running state or its vCPU is preempted, we can give
up our vCPU slices in pv_wait_node() ASAP.
Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: longman@redhat.com
Link: http://lkml.kernel.org/r/1484035006-6787-1-git-send-email-xinhui.pan@linux.vnet.ibm.com
[ Fixed typos in the changelog, removed ugly linebreak from the code. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/locking/qspinlock_paravirt.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
index e3b5520..e6b2f7a 100644
--- a/kernel/locking/qspinlock_paravirt.h
+++ b/kernel/locking/qspinlock_paravirt.h
@@ -263,7 +263,7 @@ pv_wait_early(struct pv_node *prev, int loop)
if ((loop & PV_PREV_CHECK_MASK) != 0)
return false;
- return READ_ONCE(prev->state) != vcpu_running;
+ return READ_ONCE(prev->state) != vcpu_running || vcpu_is_preempted(prev->cpu);
}
/*
^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2017-01-12 10:07 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-01-10 7:56 [PATCH v2] locking/pvqspinlock: Wait early if vCPU is preempted Pan Xinhui
2017-01-12 10:06 ` [tip:locking/core] locking/pvqspinlock: Don't wait " tip-bot for Pan Xinhui
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).