Re: Perfromance drop on SCSI hard disk

From: Alex,Shi
Date: Tue May 17 2011 - 02:10:56 EST

On Mon, 2011-05-16 at 16:37 +0800, Alex,Shi wrote:
> > > what I mean is current sdev (other devices too) can still be added into
> > > starved list, so only does async execute for current q isn't enough,
> > > we'd better put whole __scsi_run_queue into workqueue. something like
> > > below on top of yours, untested. Not sure if there are other recursive
> > > cases.
> > verified the regression can be fully fixed by your patch (with my
> > suggested fix to avoid race). Can we put a formal patch upstream?
> Yes, we tested Jens patch alone and plus Shaohua's patch too. Both of
> them recovered SAS disk performance too. Now I am testing them on SSD
> disk with kbuild and fio cases, In theory, they will both work.

As expected, both patches has no effect on SSD disks in JBD.

> >
> > Thanks,
> > Shaohua
> >

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