From: Adrian Hunter <adrian.hunter@intel.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: "Martin K . Petersen" <martin.petersen@oracle.com>,
"James E . J . Bottomley" <jejb@linux.vnet.ibm.com>,
Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
Johannes Thumshirn <jthumshirn@suse.de>,
Bart Van Assche <Bart.VanAssche@wdc.com>,
linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
Stanislav Nijnikov <stanislav.nijnikov@wdc.com>,
Evan Green <evgreen@chromium.org>,
Vinayak Holikatti <vinholikatti@gmail.com>,
Janek Kotas <jank@cadence.com>,
Vivek Gautam <vivek.gautam@codeaurora.org>,
Asutosh Das <asutoshd@codeaurora.org>,
Subhash Jadavani <subhashj@codeaurora.org>,
Sayali Lokhande <sayalil@codeaurora.org>,
Li Wei <liwei213@huawei.com>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Jaegeuk Kim <jaegeuk@kernel.org>,
Alim Akhtar <alim.akhtar@samsung.com>,
Alex Lemberg <Alex.Lemberg@sandisk.com>
Subject: Re: [PATCH RFC] scsi: ufs: Disable blk-mq for now
Date: Fri, 14 Sep 2018 09:17:14 +0300 [thread overview]
Message-ID: <2fdfc038-5b86-243c-9b0a-f294d281e5c0@intel.com> (raw)
In-Reply-To: <20180914015237.GC11059@ming.t460p>
On 14/09/18 04:52, Ming Lei wrote:
> On Thu, Sep 13, 2018 at 03:15:39PM +0300, Adrian Hunter wrote:
>> On 13/09/18 15:05, Ming Lei wrote:
>>> On Thu, Sep 13, 2018 at 02:28:48PM +0300, Adrian Hunter wrote:
>>>> blk-mq does not support runtime pm, so disable blk-mq support for now.
>>>
>>> So could you describe a bit what the issue you are trying to fix?
>>
>> UFS is a low-power solution, so we must be able to runtime suspend.
>>
>>>
>>> This is host level runtime PM you are trying to address, and if blk-mq
>>> runtime isn't enabled, I guess the host won't be runtime suspended at all
>>> because some of its descendant are always active.
>>>
>>> So seems we need to do nothing for preventing the host controller from
>>> entering runtime suspend.
>>
>> We don't want to prevent the host controller from runtime suspending, quite
>> the opposite.
>
> OK, got it.
>
> However, in previous discussion, it is strongly objected to use
> per-driver/device .use_blk_mq switch, so not sure if this way can
> be accepted.
It is only needed for 4.19 so far. Otherwise just revert d5038a13eca7
("scsi: core: switch to scsi-mq by default")
>
> BTW, I just posted the runtime PM enablement patches[1] for blk-mq,
> and I verified that it works fine and passed blktests & xfstest & my
> other sanity tests, could you try it on UFS?
>
> [1] https://marc.info/?l=linux-block&m=153684095523409&w=2
I will give it a go.
Obviously, if those patches go in, we wouldn't need to disable blk-mq
anymore, but that isn't until 4.20 at least.
next prev parent reply other threads:[~2018-09-14 6:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-13 11:28 [PATCH RFC] scsi: ufs: Disable blk-mq for now Adrian Hunter
2018-09-13 12:05 ` Ming Lei
2018-09-13 12:15 ` Adrian Hunter
2018-09-14 1:52 ` Ming Lei
2018-09-14 6:17 ` Adrian Hunter [this message]
2018-09-14 13:03 ` Adrian Hunter
2018-09-20 6:58 ` Christoph Hellwig
2018-09-21 1:59 ` Martin K. Petersen
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