From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "keith.busch@linux.intel.com" <keith.busch@linux.intel.com>
Cc: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"sagi@grimberg.me" <sagi@grimberg.me>, "hch@lst.de" <hch@lst.de>,
"ming.lei@redhat.com" <ming.lei@redhat.com>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"jianchao.w.wang@oracle.com" <jianchao.w.wang@oracle.com>,
"keith.busch@intel.com" <keith.busch@intel.com>
Subject: Re: [RFC PATCH] blk-mq: move timeout handling from queue to tagset
Date: Wed, 18 Jul 2018 18:34:07 +0000 [thread overview]
Message-ID: <adbe32bb3da7b0d405a57a176888be40f76581cb.camel@wdc.com> (raw)
In-Reply-To: <20180718174534.GC30873@localhost.localdomain>
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On Wed, 2018-07-18 at 11:45 -0600, Keith Busch wrote:
+AD4- On Wed, Jul 18, 2018 at 05:18:45PM +-0000, Bart Van Assche wrote:
+AD4- +AD4- On Wed, 2018-07-18 at 11:00 -0600, Keith Busch wrote:
+AD4- +AD4- +AD4- - cancel+AF8-work+AF8-sync(+ACY-q-+AD4-timeout+AF8-work)+=
ADs-
+AD4- +AD4- +AD4- -
+AD4- +AD4- +AD4- if (q-+AD4-mq+AF8-ops) +AHs-
+AD4- +AD4- +AD4- struct blk+AF8-mq+AF8-hw+AF8-ctx +ACo-hctx+ADs-
+AD4- +AD4- +AD4- int i+ADs-
+AD4- +AD4- +AD4- +AEAAQA- -415,6 +-412,8 +AEAAQA- void blk+AF8-sync+AF8-qu=
eue(struct request+AF8-queue +ACo-q)
+AD4- +AD4- +AD4- queue+AF8-for+AF8-each+AF8-hw+AF8-ctx(q, hctx, i)
+AD4- +AD4- +AD4- cancel+AF8-delayed+AF8-work+AF8-sync(+ACY-hctx-+AD4-r=
un+AF8-work)+ADs-
+AD4- +AD4- +AD4- +AH0- else +AHs-
+AD4- +AD4- +AD4- +- del+AF8-timer+AF8-sync(+ACY-q-+AD4-timeout)+ADs-
+AD4- +AD4- +AD4- +- cancel+AF8-work+AF8-sync(+ACY-q-+AD4-timeout+AF8-work=
)+ADs-
+AD4- +AD4- +AD4- cancel+AF8-delayed+AF8-work+AF8-sync(+ACY-q-+AD4-delay=
+AF8-work)+ADs-
+AD4- +AD4- +AD4- +AH0-
+AD4- +AD4- +AD4- +AH0-
+AD4- +AD4-=20
+AD4- +AD4- What is the impact of this change on the md driver, which is th=
e only driver
+AD4- +AD4- that calls blk+AF8-sync+AF8-queue() directly? What will happen =
if timeout processing
+AD4- +AD4- happens concurrently with or after blk+AF8-sync+AF8-queue() has=
returned?
+AD4-=20
+AD4- That's a make+AF8-request+AF8-fn stacking driver, right? There should=
be
+AD4- no impact in that case, since the change above affects only mq.
+AD4-=20
+AD4- I'm actually a little puzzled why md calls blk+AF8-sync+AF8-queue. Ar=
e the
+AD4- queue timers ever used for bio-based drivers?
Hello Keith,
For all md drivers that I verified calling md+AF8-make+AF8-request() trigge=
rs one or
more generic+AF8-make+AF8-request() calls for the underlying devices. So it=
's not
clear to me why the md driver calls blk+AF8-sync+AF8-queue().
Bart.=
next prev parent reply other threads:[~2018-07-18 18:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-18 17:00 [RFC PATCH] blk-mq: move timeout handling from queue to tagset Keith Busch
2018-07-18 17:18 ` Bart Van Assche
2018-07-18 17:45 ` Keith Busch
2018-07-18 18:34 ` Bart Van Assche [this message]
2018-07-19 9:15 ` jianchao.wang
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