Messages in this thread Patch in this message | | | Subject | Re: [PATCH] Fix WARN_ON / WARN_ON_ONCE regression | Date | Tue, 3 Oct 2006 23:24:27 -0400 | From | Andrew James Wade <> |
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On Tuesday 03 October 2006 21:14, Andrew Morton wrote: > There are changes here: in the old code we'll avoid reading the static > variable. In the new code we'll read the static variable, but we'll avoid > evaluating the condition.
Tim Chen's patch goes back to the old behaviour. I suspect the cache misses on __warn_once is what he is measuring. If so, the (untested) patch below should reduce the cache misses back to those of the old code.
signed-off-by: Andrew Wade <andrew.j.wade@gmail.com> diff -rupN a/include/asm-generic/bug.h b/include/asm-generic/bug.h --- a/include/asm-generic/bug.h 2006-10-03 13:58:40.000000000 -0400 +++ b/include/asm-generic/bug.h 2006-10-03 23:17:37.000000000 -0400 @@ -45,9 +45,10 @@ static int __warn_once = 1; \ typeof(condition) __ret_warn_once = (condition);\ \ - if (likely(__warn_once)) \ - if (WARN_ON(__ret_warn_once)) \ + if (unlikely(__ret_warn_once) && __warn_once) { \ __warn_once = 0; \ + WARN_ON(1); \ + }; \ unlikely(__ret_warn_once); \ }) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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