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On Wed, 14 Sep 2005, Chris White wrote: > That's correct, gcc 3.4 started the -mtune flag. Chances are if you really > want the -mtune optimizations you're going to have to upgrade to gcc 3.4 or > greater. > > > This, of course, heavily penalizes P4's (the notorious inc/dec). > > Are you referring to cpu cycle counts? Is there certain code that causes the > kernel to perform that unfavorably by a large scale? It's documented as being suboptimal to use inc/dec due to it modifying all of eflags resulting in dependency related stalls. add/sub only modifies one bit of eflags so is more optimal. However there is a problem of increased code size with add/sub. But i've never benchmarked all of this ;) - 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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