From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "ming.lei@redhat.com" <ming.lei@redhat.com>
Cc: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"hch@infradead.org" <hch@infradead.org>,
"snitzer@redhat.com" <snitzer@redhat.com>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"jejb@linux.vnet.ibm.com" <jejb@linux.vnet.ibm.com>,
"loberman@redhat.com" <loberman@redhat.com>,
"dm-devel@redhat.com" <dm-devel@redhat.com>
Subject: Re: [PATCH 1/5] blk-mq: introduce BLK_STS_DEV_RESOURCE
Date: Tue, 23 Jan 2018 22:01:37 +0000 [thread overview]
Message-ID: <1516744896.3339.41.camel@wdc.com> (raw)
In-Reply-To: <20180123165914.GH13277@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: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"hch@infradead.org" <hch@infradead.org>,
"snitzer@redhat.com" <snitzer@redhat.com>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"jejb@linux.vnet.ibm.com" <jejb@linux.vnet.ibm.com>,
"loberman@redhat.com" <loberman@redhat.com>,
"dm-devel@redhat.com" <dm-devel@redhat.com>
Subject: Re: [PATCH 1/5] blk-mq: introduce BLK_STS_DEV_RESOURCE
Date: Tue, 23 Jan 2018 22:01:37 +0000 [thread overview]
Message-ID: <1516744896.3339.41.camel@wdc.com> (raw)
In-Reply-To: <20180123165914.GH13277@ming.t460p>
On Wed, 2018-01-24 at 00:59 +0800, Ming Lei wrote:
> How is that enough to fix the IO hang when driver returns STS_RESOURCE
> and the queue is idle? If you want to follow previous dm-rq's way of
> call blk_mq_delay_run_hw_queue() in .queue_rq(), the same trick need
> to be applied to other drivers too, right?
>
> Unfortunately most of STS_RESOURCE don't use this trick, but they need
> to be handled.
>
> The patch of 'blk-mq: introduce BLK_STS_DEV_RESOURCE' can fix all these
> cases.
The goal of my proposal was to address the race between running the queue and
adding requests back to the dispatch queue only. Regarding the I/O hangs that
can occur if a block driver returns BLK_STS_RESOURCE: since all of these can
be addressed by inserting blk_mq_delay_run_hw_queue() calls in the affected
block drivers I prefer to modify the block drivers instead of making the
blk-mq core even more complicated.
Thanks,
Bart.
next prev parent reply other threads:[~2018-01-23 22:01 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-22 3:35 [PATCH 0/5] blk-mq & dm: fix IO hang and deal with one performance issue Ming Lei
2018-01-22 3:35 ` [PATCH 1/5] blk-mq: introduce BLK_STS_DEV_RESOURCE Ming Lei
2018-01-22 16:32 ` Christoph Hellwig
2018-01-22 16:49 ` Bart Van Assche
2018-01-22 16:49 ` Bart Van Assche
2018-01-23 0:57 ` Ming Lei
2018-01-23 16:17 ` Bart Van Assche
2018-01-23 16:26 ` Ming Lei
2018-01-23 16:37 ` Bart Van Assche
2018-01-23 16:41 ` Ming Lei
2018-01-23 16:47 ` Bart Van Assche
2018-01-23 16:47 ` Bart Van Assche
2018-01-23 16:49 ` Ming Lei
2018-01-23 16:54 ` Bart Van Assche
2018-01-23 16:54 ` Bart Van Assche
2018-01-23 16:59 ` Ming Lei
2018-01-23 16:59 ` Ming Lei
2018-01-23 22:01 ` Bart Van Assche [this message]
2018-01-23 22:01 ` Bart Van Assche
2018-01-24 2:31 ` Ming Lei
2018-01-22 3:35 ` [PATCH 2/5] dm-rq: handle dispatch exception in dm_dispatch_clone_request() Ming Lei
2018-01-22 3:35 ` Ming Lei
2018-01-22 3:35 ` [PATCH 3/5] dm-rq: return BLK_STS_* from map_request() Ming Lei
2018-01-22 3:35 ` Ming Lei
2018-01-22 5:35 ` Ming Lei
2018-01-22 3:35 ` [PATCH 4/5] blk-mq: introduce blk_get_request_notify Ming Lei
2018-01-22 10:19 ` Ming Lei
2018-01-22 17:13 ` Bart Van Assche
2018-01-22 17:13 ` Bart Van Assche
2018-01-23 1:29 ` Ming Lei
2018-01-22 3:35 ` [PATCH 5/5] dm-mpath: use blk_mq_alloc_request_notify for allocating blk-mq req Ming Lei
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