From: Jeremy Fitzhardinge <jeremy@goop.org>
To: tim.c.chen@linux.intel.com
Cc: herbert@gondor.apana.org.au, akpm@osdl.org,
linux-kernel@vger.kernel.org, leonid.ananiev@intel.com
Subject: Re: [PATCH] Fix WARN_ON / WARN_ON_ONCE regression
Date: Tue, 03 Oct 2006 17:06:28 -0700 [thread overview]
Message-ID: <4522FB04.1080001@goop.org> (raw)
In-Reply-To: <1159916644.8035.35.camel@localhost.localdomain>
Tim Chen wrote:
> Hi Herbet,
>
> The patch "Let WARN_ON/WARN_ON_ONCE return the condition"
> http://kernel.org/git/?
> p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=684f978347deb42d180373ac4c427f82ef963171
>
> introduced 40% more 2nd level cache miss to tbench workload
> being run in a loop back mode on a Core 2 machine. I think the
> introduction of the local variables to WARN_ON and WARN_ON_ONCE
>
> typeof(x) __ret_warn_on = (x);
> typeof(condition) __ret_warn_once = (condition);
>
> results in the extra cache misses. In our test workload profile, we see
> heavily used functions like do_softirq and local_bh_enable
> takes a lot longer to execute.
>
> The modification below helps fix the problem. I made a slight
> modification to sched.c to get around a gcc bug.
>
How does the generated code change? Doesn't evaluating the condition
multiple times have the potential to cause problems?
J
next prev parent reply other threads:[~2006-10-04 0:06 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-03 23:04 [PATCH] Fix WARN_ON / WARN_ON_ONCE regression Tim Chen
2006-10-03 23:19 ` Tim Chen
2006-10-04 0:06 ` Jeremy Fitzhardinge [this message]
2006-10-03 23:47 ` Tim Chen
2006-10-04 4:39 ` Jeremy Fitzhardinge
2006-10-04 13:21 ` Tim Chen
2006-10-04 16:30 ` Andrew Morton
2006-10-04 16:22 ` Tim Chen
2006-10-04 17:34 ` Andrew Morton
2006-10-04 20:43 ` Tim Chen
2006-10-10 1:09 ` Tim Chen
2006-10-10 13:04 ` Steven Rostedt
2006-10-10 15:41 ` Tim Chen
2006-10-10 20:03 ` Jeremy Fitzhardinge
2006-10-04 0:07 ` Andrew Morton
2006-10-03 23:42 ` Tim Chen
2006-10-04 0:09 ` Tim Chen
2006-10-04 1:14 ` Andrew Morton
2006-10-04 1:47 ` Nick Piggin
2006-10-04 3:24 ` Andrew James Wade
2006-10-04 3:32 ` Andrew Morton
2006-10-04 16:47 ` Andrew James Wade
2006-10-04 22:06 ` Andrew Morton
2006-10-05 8:13 ` Andrew James Wade
2006-10-05 8:36 ` Andrew Morton
2006-10-05 21:31 ` Andrew James Wade
2006-10-05 21:01 ` Tim Chen
-- strict thread matches above, loose matches on Subject: below --
2006-10-04 16:57 Ananiev, Leonid I
2006-10-04 17:28 ` Andrew Morton
2006-10-08 0:28 ` Steven Rostedt
2006-10-08 0:39 ` Jeremy Fitzhardinge
2006-10-04 21:55 Ananiev, Leonid I
2006-10-05 21:37 ` Andrew Morton
2006-10-05 21:43 ` Jeremy Fitzhardinge
2006-10-05 21:52 ` Andrew Morton
2006-10-05 22:02 ` Herbert Xu
2006-10-05 22:40 ` Jeremy Fitzhardinge
2006-10-05 21:51 ` Tim Chen
2006-10-06 16:11 ` Andrew James Wade
2006-10-06 4:06 Ananiev, Leonid I
2006-10-10 21:05 Ananiev, Leonid I
2006-10-10 21:17 ` Steven Rostedt
2006-10-10 21:41 ` Roland Dreier
2006-10-10 22:59 ` Jeremy Fitzhardinge
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