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Andi, On Thu, 08 Jun 2006, Andi Kleen wrote: > > AFAIK gcc mostly uses the probability information for block reordering > to make the fast path fall through without jumps. After a quick try on RH EL4 gcc 3.4.4-2 it appears that -fno-reorder-blocks indeed defeats __builtin_expect() as you say. (Which is rather bizarre as __builtin_expect() no longer does what one expects.) I think that I'm going to strip it out for my externally compiled modules. Otherwise, the source code rearrangements necessary to get the same effect will make the source code unreadable and generate larger code, which I think is worse than those effects on the assembler code. Thanks again. --brian - 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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