Messages in this thread | | | Date | Wed, 15 Jun 2005 01:54:01 +0200 | From | Andi Kleen <> | Subject | Re: [PATCH] Move some variables into the "most_readonly" section?? |
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On Tue, Jun 14, 2005 at 04:27:55PM -0700, Christoph Lameter wrote: > On Wed, 15 Jun 2005, Andi Kleen wrote: > > > > If these maps would start in the middle of a cacheline then additional > > > cacheline fetches may become necessary to scan an array etc. > > > > But the CPUs do prefetching anyways for that. Do you have numbers > > that this is actually worth it? > > Its not only for scanning an array. A struct may contains a lot of > related information like for example boot_cpu_data. Aligning > increases locality and the likelyhood that no additional cachelines have > to be fetched.
On the other hand it will increase the overall working set so there might be more cache misses again. It's a trade off and the outcome is not clear.
Do you have numbers?
When in doubt I would suggest the less wasteful in memory solution.
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