Date: Wed, 24 Oct 2012 12:13:38 -0700 From: Jim Harris <jimharris@freebsd.org> To: freebsd-arch@freebsd.org Subject: CACHE_LINE_SIZE on x86 Message-ID: <CAJP=Hc_F%2B-RdD=XZ7ikBKVKE_XW88Y35Xw0bYE6gGURLPDOAWw@mail.gmail.com>
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While investigating padding of the ULE scheduler locks (r242014), I recently discovered that CACHE_LINE_SIZE on x86 is defined as 128 (not 64). From what I can tell from svn logs, this was to account for 128 byte cache "sectors" that existed on the NetBurst micro architecture CPUs. I'm curious if there's been consideration in changing this back to 64? With maybe a kernel config option to modify it? On 2S systems (but not on 1S systems), I see a benefit using CACHE_LINE_SIZE=128 for the scheduler locks. I suspect this is related to data prefetching but am still running experiments to verify. Thanks, -Jim
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