From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "ming.lei@redhat.com" <ming.lei@redhat.com>
Cc: "jthumshirn@suse.de" <jthumshirn@suse.de>,
"hch@infradead.org" <hch@infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"axboe@fb.com" <axboe@fb.com>,
"oleksandr@natalenko.name" <oleksandr@natalenko.name>,
"jejb@linux.vnet.ibm.com" <jejb@linux.vnet.ibm.com>,
"cavery@redhat.com" <cavery@redhat.com>
Subject: Re: [PATCH V4 08/10] block: allow to allocate req with RQF_PREEMPT when queue is preempt frozen
Date: Thu, 14 Sep 2017 13:37:14 +0000 [thread overview]
Message-ID: <1505396232.2898.13.camel@wdc.com> (raw)
In-Reply-To: <20170914011532.GA16105@ming.t460p>
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WARNING: multiple messages have this Message-ID (diff)
From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "ming.lei@redhat.com" <ming.lei@redhat.com>
Cc: "jthumshirn@suse.de" <jthumshirn@suse.de>,
"hch@infradead.org" <hch@infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"axboe@fb.com" <axboe@fb.com>,
"oleksandr@natalenko.name" <oleksandr@natalenko.name>,
"jejb@linux.vnet.ibm.com" <jejb@linux.vnet.ibm.com>,
"cavery@redhat.com" <cavery@redhat.com>
Subject: Re: [PATCH V4 08/10] block: allow to allocate req with RQF_PREEMPT when queue is preempt frozen
Date: Thu, 14 Sep 2017 13:37:14 +0000 [thread overview]
Message-ID: <1505396232.2898.13.camel@wdc.com> (raw)
In-Reply-To: <20170914011532.GA16105@ming.t460p>
On Thu, 2017-09-14 at 09:15 +0800, Ming Lei wrote:
> On Wed, Sep 13, 2017 at 07:07:53PM +0000, Bart Van Assche wrote:
> > On Thu, 2017-09-14 at 01:48 +0800, Ming Lei wrote:
> > > No, that patch only changes blk_insert_cloned_request() which is used
> > > by dm-rq(mpath) only, nothing to do with the reported issue during
> > > suspend and sending SCSI Domain validation.
> >
> > There may be other ways to fix the SCSI domain validation code.
>
> Again the issue isn't in domain validation, it is in quiesce,
> so we need to fix quiesce, instead of working around transport_spi.
>
> Also What is the other way? Why not this patchset?
Sorry if I had not made this clear enough but I don't like the approach of
this patch series so please do not expect any "Reviewed-by" tags from me.
As the discussion about v4 of this patch series made clear the interaction
between blk_cleanup_queue() and the changes introduced by this patch series
in blk_get_request() is subtle and hard to analyze. The blk-mq core is
already complicated. In my view patches that make the blk-mq core simpler
are much more welcome than patches that make the blk-mq core more
complicated.
Since I expect that any fix for the interaction between blk-mq and power
management will be integrated in kernel v4.15 at earliest there is no reason
to rush. My proposal is to wait a few weeks and to see whether anyone comes
up with a better solution.
Bart.
next prev parent reply other threads:[~2017-09-14 13:38 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-11 11:10 [PATCH V4 0/10] block/scsi: safe SCSI quiescing Ming Lei
2017-09-11 11:10 ` [PATCH V4 01/10] blk-mq: only run hw queues for blk-mq Ming Lei
2017-09-11 11:10 ` [PATCH V4 02/10] block: tracking request allocation with q_usage_counter Ming Lei
2017-09-11 11:10 ` [PATCH V4 03/10] blk-mq: rename blk_mq_[freeze|unfreeze]_queue Ming Lei
2017-09-11 11:10 ` [PATCH V4 04/10] blk-mq: rename blk_mq_freeze_queue_wait as blk_freeze_queue_wait Ming Lei
2017-09-11 11:10 ` [PATCH V4 05/10] block: rename .mq_freeze_wq and .mq_freeze_depth Ming Lei
2017-09-11 11:10 ` [PATCH V4 06/10] block: pass flags to blk_queue_enter() Ming Lei
2017-09-11 11:10 ` [PATCH V4 07/10] block: introduce preempt version of blk_[freeze|unfreeze]_queue Ming Lei
2017-09-11 11:10 ` [PATCH V4 08/10] block: allow to allocate req with RQF_PREEMPT when queue is preempt frozen Ming Lei
2017-09-11 16:03 ` Bart Van Assche
2017-09-11 16:03 ` Bart Van Assche
2017-09-12 3:40 ` Ming Lei
2017-09-13 16:48 ` Ming Lei
2017-09-13 17:28 ` Bart Van Assche
2017-09-13 17:28 ` Bart Van Assche
2017-09-13 17:48 ` Ming Lei
2017-09-13 19:07 ` Bart Van Assche
2017-09-13 19:07 ` Bart Van Assche
2017-09-14 1:15 ` Ming Lei
2017-09-14 13:37 ` Bart Van Assche [this message]
2017-09-14 13:37 ` Bart Van Assche
2017-09-14 16:18 ` Ming Lei
2017-09-11 11:10 ` [PATCH V4 09/10] SCSI: transport_spi: resume a quiesced device Ming Lei
2017-09-11 11:10 ` [PATCH V4 10/10] SCSI: preempt freeze block queue when SCSI device is put into quiesce Ming Lei
2017-09-11 21:24 ` [PATCH V4 0/10] block/scsi: safe SCSI quiescing Oleksandr Natalenko
2017-09-11 21:24 ` Oleksandr Natalenko
2017-09-12 19:03 ` Cathy Avery
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