Re: [patch 0/8] mutex subsystem, ANNOUNCE

From: Nick Piggin
Date: Wed Dec 21 2005 - 21:36:18 EST


Jes Sorensen wrote:
"Ingo" == Ingo Molnar <mingo@xxxxxxx> writes:


Ingo> this is the latest version of the mutex subsystem
Ingo> patch-queue. It consists of the following patches:

[snip]

Ingo> the patches are against Linus' latest tree, and were tested on
Ingo> i386, x86_64 and ia64. [the tests were also done in
Ingo> DEBUG_MUTEX_FULL mode, to make sure the code works
Ingo> fine. MUTEX_FULL support is not included in this patchqueue].

Hi,

I have been working with Ingo on porting this to ehe ia64 and run a
bunch of benchmarks using the DEBUG_MUTEX_FULL settings to see how it
behaves on various sized systems (8, 24 and 60 CPUs). In general I am
seeing speedups of roughly a factor 4 on XFS and 2.4 on TMPFS.

Below you will find the results. It's basically the same kernel
version with and without the mutex patch running in DEBUG_MUTEX_FULL
mode without debugging enabled. No other config options were changed.

I won't rule out any pilot errors, but at least it gives an idea about
the change in performance for a specific workload on different sized
boxes.


It would be nice to first do a run with a fair implementation of
mutexes.

The improvements are definitely large enough that you cannot dismiss
the unfair implementation... I wonder if you can record a maximum
cost per op? That would be more interesting than either average or
standard deviation.

Thanks,
Nick

--
SUSE Labs, Novell Inc.

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