Messages in this thread | | | Date | Wed, 26 May 1999 23:17:32 +0200 | From | Artur Skawina <> | Subject | Re: [patch] checksum P6 asm buffer overflow fix + 686 improvements |
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Andrea Arcangeli wrote: > > I would be still more convinced if the mmx routine would run some bit > faster. The numbers was something like 60 unit of time for mmx and 63 > units of time for the current code + my patch.
<disclaimer> i'm _not_ saying all #s i quote are 100% reliable, I'm seeing a bit to much what appears to be random variations (alignment?). [yes, all are for hot caches - i only wanted to compare different solutions wrt eachover]. at least some #s, are better than none. </disclaimer>
note that the current 686 code wasn't optimized fully - I'm was able to get a 2-3% speedup simply by moving instructions around to better fit the 4-1-1 scheme (+other minor changes). So, if I assume correctly that the numbers you mention above don't include the fpu manipulation cost, I doubt the mmx stuff would be a win.
> It would be interesting > also to implement a copy-user mmx (as suggested some seconds ago from > Artur) to see if using movq instead of movl would improve performances > some bit more.
I will look at the csum© routine, and see if it's possible to squize a few cycles out of that too.
[...looking at the usage peaks...] hmm, I'll have to recheck this later (my data gathering patch missed one case), but I suspect we can get a noticable improvement here too.
artur
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