Re: Perfromance drop on SCSI hard disk

From: Jens Axboe
Date: Tue May 17 2011 - 03:20:42 EST

On 2011-05-17 08:09, Alex,Shi wrote:
> 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.

I will queue up the combined patch, it looks fine from here as well.

Jens Axboe

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