From: tip-bot for Pan Xinhui <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: mingo@kernel.org, torvalds@linux-foundation.org, efault@gmx.de,
hpa@zytor.com, peterz@infradead.org, tglx@linutronix.de,
xinhui.pan@linux.vnet.ibm.com, linux-kernel@vger.kernel.org
Subject: [tip:locking/core] locking/qspinlock: Use __this_cpu_dec() instead of full-blown this_cpu_dec()
Date: Mon, 27 Jun 2016 05:56:29 -0700 [thread overview]
Message-ID: <tip-0dceeaf599e6d9b8bd908ba4bd3dfee84aa26be2@git.kernel.org> (raw)
In-Reply-To: <1465886247-3773-1-git-send-email-xinhui.pan@linux.vnet.ibm.com>
Commit-ID: 0dceeaf599e6d9b8bd908ba4bd3dfee84aa26be2
Gitweb: http://git.kernel.org/tip/0dceeaf599e6d9b8bd908ba4bd3dfee84aa26be2
Author: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
AuthorDate: Tue, 14 Jun 2016 14:37:27 +0800
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 27 Jun 2016 11:37:41 +0200
locking/qspinlock: Use __this_cpu_dec() instead of full-blown this_cpu_dec()
queued_spin_lock_slowpath() should not worry about another
queued_spin_lock_slowpath() running in interrupt context and
changing node->count by accident, because node->count keeps
the same value every time we enter/leave queued_spin_lock_slowpath().
On some architectures this_cpu_dec() will save/restore irq flags,
which has high overhead. Use the much cheaper __this_cpu_dec() instead.
Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman.Long@hpe.com
Link: http://lkml.kernel.org/r/1465886247-3773-1-git-send-email-xinhui.pan@linux.vnet.ibm.com
[ Rewrote changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/locking/qspinlock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 7306555..b2caec7 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -619,7 +619,7 @@ release:
/*
* release the node
*/
- this_cpu_dec(mcs_nodes[0].count);
+ __this_cpu_dec(mcs_nodes[0].count);
}
EXPORT_SYMBOL(queued_spin_lock_slowpath);
prev parent reply other threads:[~2016-06-27 12:57 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-14 6:37 [PATCH v2] locking/qspinlock: Use __this_cpu_dec instead Pan Xinhui
2016-06-27 12:56 ` tip-bot for Pan Xinhui [this message]
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