Messages in this thread | | | Date | Tue, 13 Jan 2009 13:33:17 +0100 | From | Ingo Molnar <> | Subject | Re: [patch] tlb flush_data: replace per_cpu with an array |
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* Peter Zijlstra <peterz@infradead.org> wrote:
> > - char pad[SMP_CACHE_BYTES]; > > -} ____cacheline_aligned; > > + char pad[X86_INTERNODE_CACHE_BYTES]; > > +} ____cacheline_internodealigned_in_smp; > > That will make the below array 8*4096 bytes for VSMP, which pushes the > limit for memory savings up to 256 cpus.
VSMP is a clustering solution (default-disabled) that pushes L1_CACHE_BYTES to 4096 bytes (4K). That is an extremely large alignment that pushes up the BSS size ten-fold (!), so no generic Linux distribution enables it. 32K compared to 9MB bloat caused by 4K cachelines is a drop in the ocean.
Ingo
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