From: de Dinechin, Christophe (Integrity VM) <christophe.de-dinechin@hp.com>
Date: Thu, 13 Dec 2007 15:03:07 +0000 (+0000)
Subject: [IA64] Avoid unnecessary TLB flushes when allocating memory
X-Git-Tag: v2.6.24-rc6~11^2~9
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=aec103bfa60e9f72bd66a144236592f54b986a03;p=pandora-kernel.git

[IA64] Avoid unnecessary TLB flushes when allocating memory

Improve performance of memory allocations on ia64 by avoiding a global TLB
purge to purge a single page from the file cache. This happens whenever we
evict a page from the buffer cache to make room for some other allocation.

Test case: Run 'find /usr -type f | xargs cat > /dev/null' in the
background to fill the buffer cache, then run something that uses memory,
e.g. 'gmake -j50 install'. Instrumentation showed that the number of
global TLB purges went from a few millions down to about 170 over a 12
hours run of the above.

The performance impact is particularly noticeable under virtualization,
because a virtual TLB is generally both larger and slower to purge than
a physical one.

Signed-off-by: Christophe de Dinechin <ddd@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
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