tree 90c1cf2de8853dd6e3972f295d1aecfe3aee507a
parent 3cdc7fc7fd5bd1ead75758dfadef609a6e9fd3de
author de Dinechin, Christophe (Integrity VM) <christophe.de-dinechin@hp.com> 1197558187 +0000
committer Tony Luck <tony.luck@intel.com> 1198025810 -0800

[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>