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[Xen-devel] struct page_info on x86-64

To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] struct page_info on x86-64
From: "Jan Beulich" <jbeulich@xxxxxxxxxx>
Date: Tue, 03 Apr 2007 10:13:57 +0100
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I am getting the impression that struct page_info could (in the default case)
be reduced from 40 to 32 bytes after the 3.0.4/5 changes, which no longer
appear to require type_info and shadow_flags to be unsigned long (they
could both be unsigned int aka u32). The only hindrance then is cpumask_t
being defined as an array of longs, whereas this doesn't really need to be
64 bits wide unless NR_CPUS exceeds 32. Is it worth trying to change
cpumask_t for that purpose (improving performance of frame table
accesses as well as bumping supportable memory from approximately
1.6Tb to 2Tb)?

Jan

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