Re: Processes stuck on D state on Dual Opteron

[Nick Piggin <nickpiggin@yahoo.com.au>]

Chen, Kenneth W wrote:
> On Tue, Apr 12 2005, Nick Piggin wrote:
> 
>>Actually the patches I have sent you do fix real bugs, but they also
>>make the block layer less likely to recurse into page reclaim, so it
>>may be eg. hiding the problem that Neil's patch fixes.
> 
> 
> Jens Axboe wrote on Tuesday, April 12, 2005 12:08 AM
> 
>>Can you push those to Andrew? I'm quite happy with the way they turned
>>out. It would be nice if Ken would bench 2.6.12-rc2 with and without
>>those patches.
> 
> 
> 
> I like the patch a lot and already did bench it on our db setup.  However,
> I'm seeing a negative regression compare to a very very crappy patch (see
> attached, you can laugh at me for doing things like that :-).
> 

OK - if we go that way, perhaps the following patch may be the
way to do it.

> My first reaction is that the overhead is in wait queue setup and tear down
> in get_request_wait function. Throwing the following patch on top does improve
> things a bit, but we are still in the negative territory.  I can't explain why.
> Everything suppose to be faster.  So I'm staring at the execution profile at
> the moment.
> 

Hmm, that's a bit disappointing. Like you said though, I'm sure we
should be able to get better performance out of this.

I'll look at it and see if we can rework it.

-- 
SUSE Labs, Novell Inc.