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From:   Ming Lei <tom.leiming@gmail.com>
Date:   Thu, 12 Jul 2018 00:35:17 +0800
Message-ID: <CACVXFVOSssuveZDN185FUYpjX1i0ma59Cn30XBSJ1dAHDKLnLQ@mail.gmail.com>
Subject: Re: [PATCH] scsi: switch to scsi-mq by default
To:     Adrian Hunter <adrian.hunter@intel.com>
Cc:     "Martin K. Petersen" <martin.petersen@oracle.com>,
        Johannes Thumshirn <jthumshirn@suse.de>,
        Hannes Reinecke <hare@suse.de>,
        Bart Van Assche <Bart.VanAssche@sandisk.com>,
        Linux SCSI Mailinglist <linux-scsi@vger.kernel.org>,
        Linux Kernel Mailinglist <linux-kernel@vger.kernel.org>
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On Wed, Jul 11, 2018 at 4:31 PM, Adrian Hunter <adrian.hunter@intel.com> wrote:
> On 11/07/18 05:52, Martin K. Petersen wrote:
>>
>> Johannes,
>>
>>> It has been more than one year since we tried to change the default
>>> from legacy to multi queue in SCSI with commit c279bd9e406 ("scsi:
>>> default to scsi-mq"). But due to issues with suspend/resume and
>>> performance problems it had been reverted again with commit
>>> cbe7dfa26eee ("Revert "scsi: default to scsi-mq"").
>>>
>>> In the meantime there have been a substantial amount of performance
>>> improvements and suspend/resume got fixed as well, thus we can
>>> re-enable scsi-mq without a significant performance penalty.
>>
>> Applied to 4.19/scsi-queue, thanks!
>>
>
> But there is no runtime pm support, is there?  I tried enabling runtime PM
> for UFS SCSI devices with scsi-mq and it didn't work, which is a regression.

I just posted one RFC patchset for supporting runtime PM on scsi_mq, and
looks it works in my test on usb-storage.

https://marc.info/?l=linux-block&m=153132657922233&w=2

thanks,
Ming Lei