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[Qemu-devel] [Patch] Use patched function instead of re-occuring variabl

From: Daniel Egger
Subject: [Qemu-devel] [Patch] Use patched function instead of re-occuring variable check
Date: Sun, 10 Oct 2004 23:42:20 +0200


attached patch splits the functionality of cpu_get_ticks() into
two functions cpu_get_ticks_enabled() and cpu_get_ticks_disabled()
and patches the function to use either of them in
cpu_enable_ticks() resp. cpu_disable_ticks(). The conditional check
for cpu_ticks_enabled in cpu_get_ticks() was quite expensive and
this got rid of it.

Also this patch  makes all featherweights inline to profit from
better scheduling possibilities and a reduced function call overhead.

All in all this results in a net 2% speedup of the time related
functions on powerpc. However, much to my surprise, I can not sense
any improvement in the virtual machine while the host is not 100%
utilized. It seems like I hit a cache or memory bandwidth limitation
which I need to profile further...

This patch may or may not have a positive effect on i386 so it
might be a good idea to test it on such a machine before applying.
(My Athlon has a broken PSU so I can't do this ATM, sorry).

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