LKML Archive on
help / color / mirror / Atom feed
From: tip-bot for Davidlohr Bueso <>
Subject: [tip:locking/core] locking/rtmutex: Optimize setting task running after being blocked
Date: Wed, 4 Feb 2015 06:38:44 -0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Commit-ID:  afffc6c1805d98e08e778cddb644a666e78cfcfd
Author:     Davidlohr Bueso <>
AuthorDate: Sun, 1 Feb 2015 22:16:24 -0800
Committer:  Ingo Molnar <>
CommitDate: Wed, 4 Feb 2015 07:57:42 +0100

locking/rtmutex: Optimize setting task running after being blocked

We explicitly mark the task running after returning from
a __rt_mutex_slowlock() call, which does the actual sleeping
via wait-wake-trylocking. As such, this patch does two things:

(1) refactors the code so that setting current to TASK_RUNNING
    is done by __rt_mutex_slowlock(), and not by the callers. The
    downside to this is that it becomes a bit unclear when at what
    point we block. As such I've added a comment that the task
    blocks when calling __rt_mutex_slowlock() so readers can figure
    out when it is running again.

(2) relaxes setting current's state through __set_current_state(),
    instead of it's more expensive barrier alternative. There was no
    need for the implied barrier as we're obviously not planning on

Signed-off-by: Davidlohr Bueso <>
Signed-off-by: Peter Zijlstra (Intel) <>
Cc: Linus Torvalds <>
Signed-off-by: Ingo Molnar <>
 kernel/locking/rtmutex.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 7c98873..3059bc2f 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1130,6 +1130,7 @@ __rt_mutex_slowlock(struct rt_mutex *lock, int state,
+	__set_current_state(TASK_RUNNING);
 	return ret;
@@ -1188,10 +1189,9 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
 	ret = task_blocks_on_rt_mutex(lock, &waiter, current, chwalk);
 	if (likely(!ret))
+		/* sleep on the mutex */
 		ret = __rt_mutex_slowlock(lock, state, timeout, &waiter);
-	set_current_state(TASK_RUNNING);
 	if (unlikely(ret)) {
 		remove_waiter(lock, &waiter);
 		rt_mutex_handle_deadlock(ret, chwalk, &waiter);
@@ -1626,10 +1626,9 @@ int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
+	/* sleep on the mutex */
 	ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
-	set_current_state(TASK_RUNNING);
 	if (unlikely(ret))
 		remove_waiter(lock, waiter);

      reply	other threads:[~2015-02-04 14:39 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-02  6:16 [PATCH] " Davidlohr Bueso
2015-02-04 14:38 ` tip-bot for Davidlohr Bueso [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \ \ \
    --subject='Re: [tip:locking/core] locking/rtmutex: Optimize setting task running after being blocked' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

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).