Re: [PATCH] Alignment for CPU maps, add padding semantics

From: Anton Blanchard
Date: Mon Jul 12 2004 - 08:56:54 EST



Hi,

> The attached patch add missing alignments for CPU maps (cpu_online_map,
> node_2_cpu_mask, cpu_2_node, cpu_2_logical_apicid). It allows better
> cache-line utilization by having the most usable part of each map on
> same cache-line.

These bitmaps are pretty much readonly and 4 bytes on most machines and
this change makes them up to 128 bytes long. They are also naturally
aligned in the 4 byte case so cannot cross a cacheline boundary.

It makes much more sense to have all these readonly structures packed
together in the same cacheline.

Anton
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