From: Arnd Bergmann <arnd@arndb.de>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@elte.hu>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Tony Breeds <tonyb@au1.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH/RFC] mutex: Fix optimistic spinning vs. BKL
Date: Wed, 28 Apr 2010 14:06:03 +0200 [thread overview]
Message-ID: <201004281406.04080.arnd@arndb.de> (raw)
In-Reply-To: <1272429513.24542.83.camel@pasglop>
On Wednesday 28 April 2010, Benjamin Herrenschmidt wrote:
> Now, we -could- make it a bit smarter about the BKL by introducing a
> contention counter and only go out if we own the BKL and it is contended,
> but I didn't feel like this was worth the effort, time is better spent
> removing the BKL from sensitive code path instead.
Agreed.
> - for (;;) {
> + for (timeout = jiffies + 2; jiffies < timeout;) {
> [...]
> - for (;;) {
> + while (jiffies < timeout) {
This needs to use time_before() to avoid problems on jiffies wraparound.
Arnd
next prev parent reply other threads:[~2010-04-28 12:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-28 4:38 [PATCH/RFC] mutex: Fix optimistic spinning vs. BKL Benjamin Herrenschmidt
2010-04-28 4:39 ` Benjamin Herrenschmidt
2010-04-28 12:06 ` Arnd Bergmann [this message]
2010-04-28 22:35 ` Benjamin Herrenschmidt
2010-05-07 4:20 ` Tony Breeds
2010-05-07 5:30 ` Frederic Weisbecker
2010-05-07 6:01 ` Benjamin Herrenschmidt
2010-05-07 21:29 ` Frederic Weisbecker
2010-05-07 22:27 ` Benjamin Herrenschmidt
2010-05-10 7:55 ` Peter Zijlstra
2010-05-11 18:06 ` Linus Torvalds
2010-05-11 18:19 ` Peter Zijlstra
2010-05-11 21:13 ` Benjamin Herrenschmidt
2010-05-07 6:16 ` Mike Galbraith
2010-05-11 15:43 ` [tip:core/locking] " tip-bot for Tony Breeds
2010-05-11 23:05 ` Tony Breeds
2010-05-18 16:08 ` Ingo Molnar
2010-05-18 16:26 ` Linus Torvalds
2010-05-19 5:46 ` Tony Breeds
2010-05-19 7:56 ` [tip:core/urgent] " tip-bot for Tony Breeds
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