Re: Putrid Elevator Behavior 2.4.18/19

["Jeff V. Merkey" <jmerkey@vger.timpanogas.org>]

> > > Jens/Linux,
> > > 
> > > The elevator code is malfunctioning in 2.4.18/19-pre when we start 
> > > reaching the upward limits with multiple 3Ware adapters 
> > > running together.  We started seeing the problem when we went to 
> > > 64 K aligned writes with sustained > 200 MB/S writes to 
> > > multiple 3Ware adapters.  
> > > 
> > > We have verified that the 3Ware adapters are not holding the request
> > > off, but that one of the requests is getting severely starved and
> > > does not get posted to the 3Ware adapters until thousands of IOs
> > > have gone before it.  
> > > 
> > 
> > This elevator starvation problem has been identified and a patch already
> > merged into 2.4.19-pre2.
> > 
> > Can you verify the affects it produces for your workload?
> 
> I will comply.  I tested with pre-3 patches and still saw this problem??
> Let me go and check the patches I applied to verify, I may not have 
> applied the correct patch.
> 
> Jeff

I verified we were using a stock 2.4.18 kernel on the specific system 
without the pre-3 patches installed.  We have been testing with the 
latest patches but not on this system.  We will apply and retest and 
I will verify.

Jeff

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