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Date: Wed, 04 Oct 2006 11:47:05 +1000 From: Nick Piggin <nickpiggin@...oo.com.au> To: Andrew Morton <akpm@...l.org> CC: tim.c.chen@...ux.intel.com, herbert@...dor.apana.org.au, linux-kernel@...r.kernel.org, leonid.i.ananiev@...el.com Subject: Re: [PATCH] Fix WARN_ON / WARN_ON_ONCE regression Andrew Morton wrote: > On Tue, 03 Oct 2006 17:09:29 -0700 > Tim Chen <tim.c.chen@...ux.intel.com> wrote: > > >>On Tue, 2006-10-03 at 17:07 -0700, Andrew Morton wrote: >> >> >>>Perhaps the `static int __warn_once' is getting put in the same cacheline >>>as some frequently-modified thing. Perhaps try marking that as __read_mostly? >>> >> >>I've tried marking static int __warn_once as __read_mostly. However, it >>did not help with reducing the cache miss :( >> >>So I would suggest reversing the "Let WARN_ON/WARN_ON_ONCE return the >>condition" patch. It has just been added 3 days ago so reversing it >>should not be a problem. >> > > > Not yet, please. This is presently a mystery, and we need to work out > what's going on. Still, it seems kind of odd to add this IMO. Especially the WARN_ON_ONCE makes the if statement less readable. if (WARN_ON_ONCE(blah)) { } What does that mean? Without looking at the implementation, that says the condition is true at most once, when the warning is printed. What's wrong with adding WARN and WARN_ONCE, and eating the single extra line? You're always telling people to do that with assignments (which I agree with, but are _more_ readable than this WARN_ON_ONCE thing). -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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