From: Josef Bacik <jbacik@fb.com>
To: Wouter Verhelst <w@uter.be>
Cc: <axboe@fb.com>, <linux-block@vger.kernel.org>,
<kernel-team@fb.com>, <nbd-general@lists.sourceforge.net>,
<linux-kernel@vger.kernel.org>
Subject: Re: [Nbd] [PATCH][V3] nbd: add multi-connection support
Date: Thu, 29 Sep 2016 12:59:18 -0400 [thread overview]
Message-ID: <a2d8d560-41d0-e17d-90df-b1953ce00a51@fb.com> (raw)
In-Reply-To: <20160929164100.akytbkbtvziwaqqj@grep.be>
On 09/29/2016 12:41 PM, Wouter Verhelst wrote:
> On Thu, Sep 29, 2016 at 10:03:50AM -0400, Josef Bacik wrote:
>> So think of it like normal disks with multiple channels. We don't send flushes
>> down all the hwq's to make sure they are clear, we leave that decision up to the
>> application (usually a FS of course).
>
> Well, when I asked earlier, Christoph said[1] that blk-mq assumes that
> when a FLUSH is sent over one channel, and the reply comes in, that all
> commands which have been received, regardless of which channel they were
> received over, have reched disk.
>
> [1] Message-ID: <20160915122304.GA15501@infradead.org>
>
> It is impossible for nbd to make such a guarantee, due to head-of-line
> blocking on TCP.
>
Huh I missed that. Yeah that's not possible for us for sure, I think my option
idea is the less awful way forward if we want to address that limitation. Thanks,
Josef
next prev parent reply other threads:[~2016-09-29 17:00 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-28 20:01 [PATCH][V3] nbd: add multi-connection support Josef Bacik
2016-09-29 9:52 ` [Nbd] " Wouter Verhelst
2016-09-29 14:03 ` Josef Bacik
2016-09-29 16:41 ` Wouter Verhelst
2016-09-29 16:59 ` Josef Bacik [this message]
2016-10-02 16:17 ` Alex Bligh
2016-10-02 16:17 ` Alex Bligh
2016-10-03 1:47 ` Josef Bacik
2016-10-03 1:47 ` Josef Bacik
2016-10-03 7:20 ` Christoph Hellwig
2016-10-03 7:51 ` Wouter Verhelst
2016-10-03 7:57 ` Christoph Hellwig
2016-10-03 11:34 ` Alex Bligh
2016-10-03 11:34 ` Alex Bligh
2016-10-03 14:32 ` Josef Bacik
2016-10-03 14:32 ` Josef Bacik
2016-10-03 14:46 ` Alex Bligh
2016-10-03 14:46 ` Alex Bligh
2016-10-03 21:07 ` Wouter Verhelst
2016-10-04 9:35 ` Alex Bligh
2016-10-06 9:04 ` Wouter Verhelst
2016-10-06 9:41 ` Alex Bligh
2016-10-06 10:15 ` Wouter Verhelst
2016-10-06 11:04 ` Alex Bligh
2016-10-06 10:31 ` Christoph Hellwig
2016-10-06 13:09 ` Wouter Verhelst
2016-10-06 13:16 ` Christoph Hellwig
2016-10-06 13:55 ` Wouter Verhelst
2016-10-03 7:49 ` Wouter Verhelst
2016-10-11 9:00 ` Sagi Grimberg
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