Messages in this thread | | | Subject | Re: [PATCH] [RFC] [2.5 i386] GCC 3.1 -march support, PPRO_FENCE reduction, prefetch fixes and other CPU-related changes | From | Alan Cox <> | Date | 05 Aug 2002 12:26:06 +0100 |
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On Mon, 2002-08-05 at 10:53, Luca Barbieri wrote: > > If OOSTORE is defined then we can't safely use any mmx operations, so > > this is all noise and its still the case no change is required > Yes, this is only for future processors (e.g. out-order AMD/Intels or > Winchips with extended MMX).
The winchip line is dead so that bit is ok as it is. PPro is sorted with the current code. The wmb() case therefore seems resolved already. The guarantees already given by the processors are sufficient to ensure that wmb is simply a compiler optimisation barrier for other cases (and indeed the spinlock code breaks if it ceases to be true, as does an awful lot of 'other vendors' code)
For the rmb() situation then yes your fence changes may well be a win on the PIV, and would certainly be worth benchmarking. I'd be interested to see the numbers.
Alan
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