Re: [patch 00/10] [RFC] SLUB patches for more functionality, performanceand maintenance

From: Martin Bligh
Date: Mon Jul 09 2007 - 17:00:35 EST

Christoph Lameter wrote:
On Mon, 9 Jul 2007, Martin Bligh wrote:

Those numbers came from Mathieu Desnoyers (LTTng) if you
want more details.

Okay the source for these numbers is in his paper for the OLS 2006: Volume 1 page 208-209? I do not see the exact number that you referred to there.

Nope, he was a direct co-author on the paper, was
working here, and measured it.

He seems to be comparing spinlock acquire / release vs. cmpxchg. So I guess you got your material from somewhere else?

Also the cmpxchg used there is the lockless variant. cmpxchg 29 cycles w/o lock prefix and 112 with lock prefix.

I see you reference another paper by Desnoyers:

I do not see anything relevant there. Where did those numbers come from?

The lockless cmpxchg is certainly an interesting idea. Certain for some platforms I could disable preempt and then do a lockless cmpxchg.

Matheiu, can you give some more details? Obviously the exact numbers
will vary by archicture, machine size, etc, but it's a good point
for discussion.

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