From: Mike Snitzer <snitzer@redhat.com>
To: Bart Van Assche <Bart.VanAssche@wdc.com>
Cc: "ming.lei@redhat.com" <ming.lei@redhat.com>,
"dm-devel@redhat.com" <dm-devel@redhat.com>,
"hch@infradead.org" <hch@infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"axboe@fb.com" <axboe@fb.com>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>
Subject: Re: [PATCH V3 0/5] dm-rq: improve sequential I/O performance
Date: Fri, 12 Jan 2018 12:40:01 -0500 [thread overview]
Message-ID: <20180112174000.GB5134@redhat.com> (raw)
In-Reply-To: <1515778013.2396.3.camel@wdc.com>
On Fri, Jan 12 2018 at 12:26pm -0500,
Bart Van Assche <Bart.VanAssche@wdc.com> wrote:
> On Fri, 2018-01-12 at 12:18 -0500, Mike Snitzer wrote:
> > This is going upstream for 4.16:
> > https://git.kernel.org/pub/scm/linux/kernel/git/snitzer/linux.git/commit/?h=dm-4.16&id=5b18cff4baedde77e0d69bd62a13ae78f9488d89
>
> That is really gross. I have explained many times in detail on the dm-devel
> list why that blk_mq_delay_run_hw_queue() call is necessary. So I think it is
> wrong if you remove it. Isn't the responsibility of you as the device mapper
> kernel maintainer to avoid regressions instead of introducing regressions?
Please stop, seriously.
You've not explained it many times. We cannot get a straight answer
from you. No analysis that establishes that if an underlying dm-mq
multipath path is out of tags (shared or otherwise) that dm-rq core
_must_ run the hw queue after a delay.
Commit 6077c2d7060 just papers over a real blk-mq problem (that may now
be fixed). Your assertions that blk-mq would need to otherwise poll
(and waste resources so it can immediately retry) ignores that blk-mq
_should_ make progress as requests complete or if/when a path is
recovered, etc. So I'm not going to accept your dysfuctional reasoning
on this, sorry. _THAT_ is my job as a maintainer.
next prev parent reply other threads:[~2018-01-12 17:40 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-11 6:01 [PATCH V3 0/5] dm-rq: improve sequential I/O performance Ming Lei
2018-01-11 6:01 ` [PATCH V3 1/5] dm-mpath: don't call blk_mq_delay_run_hw_queue() in case of BLK_STS_RESOURCE Ming Lei
2018-01-11 6:01 ` [PATCH V3 2/5] dm-mpath: return DM_MAPIO_REQUEUE in case of rq allocation failure Ming Lei
2018-01-12 19:04 ` Bart Van Assche
2018-01-12 19:04 ` Bart Van Assche
2018-01-13 1:29 ` Ming Lei
2018-01-11 6:01 ` [PATCH V3 3/5] blk-mq: move actual issue into one helper Ming Lei
2018-01-11 22:09 ` Mike Snitzer
2018-01-11 6:01 ` [PATCH V3 4/5] blk-mq: return dispatch result to caller in blk_mq_try_issue_directly Ming Lei
2018-01-11 22:10 ` Mike Snitzer
2018-01-11 6:01 ` [PATCH V3 5/5] blk-mq: issue request directly for blk_insert_cloned_request Ming Lei
2018-01-11 22:42 ` Mike Snitzer
2018-01-11 22:07 ` [PATCH V3 0/5] dm-rq: improve sequential I/O performance Mike Snitzer
2018-01-11 22:37 ` Bart Van Assche
2018-01-11 22:37 ` Bart Van Assche
2018-01-11 22:58 ` Mike Snitzer
2018-01-11 23:27 ` Bart Van Assche
2018-01-11 23:27 ` Bart Van Assche
2018-01-12 1:43 ` Mike Snitzer
2018-01-12 1:42 ` Ming Lei
2018-01-12 1:57 ` Mike Snitzer
2018-01-12 3:33 ` Ming Lei
2018-01-12 17:18 ` Mike Snitzer
2018-01-12 17:26 ` Bart Van Assche
2018-01-12 17:26 ` Bart Van Assche
2018-01-12 17:40 ` Mike Snitzer [this message]
2018-01-12 17:46 ` Bart Van Assche
2018-01-12 17:46 ` Bart Van Assche
2018-01-12 18:06 ` Mike Snitzer
2018-01-12 18:54 ` Bart Van Assche
2018-01-12 18:54 ` Bart Van Assche
2018-01-12 19:29 ` Mike Snitzer
2018-01-12 19:53 ` Elliott, Robert (Persistent Memory)
2018-01-12 19:53 ` Elliott, Robert (Persistent Memory)
2018-01-13 0:52 ` Mike Snitzer
2018-01-13 1:00 ` Bart Van Assche
2018-01-13 1:00 ` Bart Van Assche
2018-01-13 1:37 ` Mike Snitzer
2018-01-13 15:14 ` Mike Snitzer
2018-01-12 22:31 ` Mike Snitzer
2018-01-13 15:04 ` Ming Lei
2018-01-13 15:04 ` Ming Lei
2018-01-13 15:10 ` Mike Snitzer
2018-01-12 23:17 ` Mike Snitzer
2018-01-12 23:42 ` Bart Van Assche
2018-01-12 23:42 ` Bart Van Assche
2018-01-13 0:45 ` Mike Snitzer
2018-01-13 14:34 ` Ming Lei
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