Messages in this thread | | | Subject | Re: [PATCH] 2.6 workaround for Athlon/Opteron prefetch errata | From | Alan Cox <> | Date | Mon, 15 Sep 2003 14:48:17 +0100 |
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On Llu, 2003-09-15 at 13:11, Bill Davidsen wrote: > The code to disable prefetch on Athlon is 300 bytes and hurts your PIV? > Really? I'll dig back through the code, but I recall it as adding or > deleting an entry in a table to enable prefetch. If it's affecting PIV the > code to use prefetch is seriously broken.
Big time. Its over 300 bytes long because its embedded in each inline prefetch and it causes a branch misprediction almost every time. Amazing what you find when you actually measure stuff 8)
So right now, its faster on PIV to delete the prefetch than use the current hack, and adding the Athlon fix makes Athlon and PIV faster and total memory size lower.
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