* lmbench context switch regression
@ 2003-11-05 12:28 Nick Piggin
2003-11-05 23:16 ` Nick Piggin
0 siblings, 1 reply; 2+ messages in thread
From: Nick Piggin @ 2003-11-05 12:28 UTC (permalink / raw)
To: Linus Torvalds, Andrew Morton; +Cc: linux-kernel
Hi,
I'm seeing quite a large context switch speed regression as reported
by lmbench when I patched from test9 to test9-mm2.
The obvious thing I can see from the patch is the PF_DEAD finish_task_switch
change. I don't have time to investigate further tonight though.
lmbench two 0 sized processes context switch times go from around 1.80us to
2.60us on my PIII 650 (UP).
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: lmbench context switch regression
2003-11-05 12:28 lmbench context switch regression Nick Piggin
@ 2003-11-05 23:16 ` Nick Piggin
0 siblings, 0 replies; 2+ messages in thread
From: Nick Piggin @ 2003-11-05 23:16 UTC (permalink / raw)
To: Linus Torvalds; +Cc: Andrew Morton, linux-kernel
Nick Piggin wrote:
> Hi,
> I'm seeing quite a large context switch speed regression as reported
> by lmbench when I patched from test9 to test9-mm2.
>
> The obvious thing I can see from the patch is the PF_DEAD
> finish_task_switch
> change. I don't have time to investigate further tonight though.
>
> lmbench two 0 sized processes context switch times go from around
> 1.80us to
> 2.60us on my PIII 650 (UP).
The regression is smaller when going from test9 to test9-bk. About .2us
(10%).
It does not go away when reverting the PF_DEAD change. Maybe its just lucky
alignment?
^ permalink raw reply [flat|nested] 2+ messages in thread
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