Re: [PATCH] [patch 4a/4] ipc: sem optimise simple operations

[Manfred Spraul]

On 08/17/2009 08:44 AM, Nick Piggin wrote:
> OK, well let's just get something in.
>    
Good, I would propose the that the following 7 patches should be merged:

http://lkml.org/lkml/2009/8/11/59
http://lkml.org/lkml/2009/8/11/9
http://lkml.org/lkml/2009/8/11/14
http://lkml.org/lkml/2009/8/15/163
http://lkml.org/lkml/2009/8/15/164
http://lkml.org/lkml/2009/8/15/167
http://lkml.org/lkml/2009/8/15/168

Nick: is that ok from your point of view?

> That said, I'm not too unhappy with your version if you feel strongly
> about it.
I would prefer it:
We simply don't know if a wait-for-zero list, only for single sop operations, is a step in the right direction.

Postgres uses single sop operations with just +-1 on one semaphore.
You wrote that your SAP workload also uses +-1.
According to google codesearch, apache, mozilla, mpich all use +-1.

Thus: Who uses single sop, wait for zero?
I'm just afraid that we optimize for the wrong case.

--
	Manfred

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