From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "snitzer@redhat.com" <snitzer@redhat.com>,
"mcgrof@kernel.org" <mcgrof@kernel.org>
Cc: "mwilck@suse.com" <mwilck@suse.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"agk@redhat.com" <agk@redhat.com>,
Damien Le Moal <Damien.LeMoal@wdc.com>,
"hare@suse.de" <hare@suse.de>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"yuchao0@huawei.com" <yuchao0@huawei.com>,
"ghe@suse.com" <ghe@suse.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"jaegeuk@kernel.org" <jaegeuk@kernel.org>,
"tchvatal@suse.com" <tchvatal@suse.com>,
"zren@suse.com" <zren@suse.com>
Subject: Re: dm-zoned-tools: add zoned disk udev rules for scheduler / dmsetup
Date: Thu, 14 Jun 2018 16:23:39 +0000 [thread overview]
Message-ID: <4bca9936ccc0cc67404e8da8f7a3c5948ba7e518.camel@wdc.com> (raw)
In-Reply-To: <20180614123806.GA32162@redhat.com>
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WARNING: multiple messages have this Message-ID (diff)
From: Bart Van Assche <Bart.VanAssche@wdc.com>
To: "snitzer@redhat.com" <snitzer@redhat.com>,
"mcgrof@kernel.org" <mcgrof@kernel.org>
Cc: "mwilck@suse.com" <mwilck@suse.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"agk@redhat.com" <agk@redhat.com>,
Damien Le Moal <Damien.LeMoal@wdc.com>,
"hare@suse.de" <hare@suse.de>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"yuchao0@huawei.com" <yuchao0@huawei.com>,
"ghe@suse.com" <ghe@suse.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"jaegeuk@kernel.org" <jaegeuk@kernel.org>,
"tchvatal@suse.com" <tchvatal@suse.com>,
"zren@suse.com" <zren@suse.com>
Subject: Re: dm-zoned-tools: add zoned disk udev rules for scheduler / dmsetup
Date: Thu, 14 Jun 2018 16:23:39 +0000 [thread overview]
Message-ID: <4bca9936ccc0cc67404e8da8f7a3c5948ba7e518.camel@wdc.com> (raw)
In-Reply-To: <20180614123806.GA32162@redhat.com>
On Thu, 2018-06-14 at 08:38 -0400, Mike Snitzer wrote:
> On Wed, Jun 13 2018 at 8:11pm -0400,
> Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> > 1) scheduler setup
>
> This is wrong.. if zoned devices are so dependent on deadline or
> mq-deadline then the kernel should allow them to be hardcoded. I know
> Jens removed the API to do so but the fact that drivers need to rely on
> hacks like this udev rule to get a functional device is proof we need to
> allow drivers to impose the scheduler used.
Hello Mike,
As you know the Linux kernel block layer stack can reorder requests. However,
for zoned block devices it is essential that the block device receives write
requests in the same order as these were submitted by the (user space)
application or by the (kernel) filesystem. After a long debate the choice was
made to make I/O schedulers responsible for guaranteeing to preserve the write
order. Today only the deadline scheduler guarantees that the write order is
preserved. Hence the udev rule that sets the deadline scheduler for zoned
block devices.
Bart.
next prev parent reply other threads:[~2018-06-14 16:23 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-14 0:11 [PATCH] dm-zoned-tools: add zoned disk udev rules for scheduler / dmsetup Luis R. Rodriguez
2018-06-14 10:01 ` Damien Le Moal
2018-06-14 10:01 ` Damien Le Moal
2018-06-14 13:39 ` Bart Van Assche
2018-06-14 13:39 ` Bart Van Assche
2018-06-14 13:42 ` Christoph Hellwig
2018-06-15 11:07 ` Martin Wilck
2018-06-15 11:07 ` Martin Wilck
2018-06-14 12:38 ` Mike Snitzer
2018-06-14 16:23 ` Bart Van Assche [this message]
2018-06-14 16:23 ` Bart Van Assche
2018-06-14 17:37 ` Luis R. Rodriguez
2018-06-14 17:46 ` Luis R. Rodriguez
2018-06-14 17:58 ` Mike Snitzer
2018-06-15 9:59 ` Damien Le Moal
2018-06-15 9:59 ` Damien Le Moal
2018-06-15 14:50 ` Mike Snitzer
2018-06-15 9:00 ` Damien Le Moal
2018-06-15 9:00 ` Damien Le Moal
2018-06-14 16:19 ` [PATCH] " Bart Van Assche
2018-06-14 16:19 ` Bart Van Assche
2018-06-14 17:44 ` Luis R. Rodriguez
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