From: Mike Snitzer <snitzer@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>,
josef@toxicpanda.com, bvanassche@acm.org, corbet@lwn.net,
kernel-team@android.com, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
song@kernel.org, dm-devel@redhat.com,
linux-kselftest@vger.kernel.org, shuah@kernel.org,
agk@redhat.com, michael.christie@oracle.com
Subject: Re: [PATCH v1 0/5] dm: dm-user: New target that proxies BIOs to userspace
Date: Tue, 22 Dec 2020 09:36:16 -0500 [thread overview]
Message-ID: <20201222143616.GB12885@redhat.com> (raw)
In-Reply-To: <20201222133246.GA5099@infradead.org>
On Tue, Dec 22 2020 at 8:32am -0500,
Christoph Hellwig <hch@infradead.org> wrote:
> On Mon, Dec 14, 2020 at 07:00:57PM -0800, Palmer Dabbelt wrote:
> > I haven't gotten a whole lot of feedback, so I'm inclined to at least have some
> > reasonable performance numbers before bothering with a v2.
>
> FYI, my other main worry beside duplicating nbd is that device mapper
> really is a stacked interface that sits on top of other block device.
> Turning this into something else that just pipes data to userspace
> seems very strange.
I agree. Only way I'd be interested is if it somehow tackled enabling
much more efficient IO. Earlier discussion in this thread mentioned
that zero-copy and low overhead wasn't a priority (because it is hard,
etc). But the hard work has already been done with io_uring. If
dm-user had a prereq of leaning heavily on io_uring and also enabled IO
polling for bio-based then there may be a win to supporting it.
But unless lower latency (or some other more significant win) is made
possible I just don't care to prop up an unnatural DM bolt-on.
Mike
next prev parent reply other threads:[~2020-12-22 14:38 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 21:58 [PATCH v1 0/5] dm: dm-user: New target that proxies BIOs to userspace Palmer Dabbelt
2020-12-03 21:58 ` [PATCH v1 1/5] Documentation: Describe dm-user Palmer Dabbelt
2020-12-03 21:58 ` [PATCH v1 2/5] uapi: Add dm-user structure definition Palmer Dabbelt
2020-12-03 21:58 ` [PATCH v1 3/5] dm: dm-user: New target that proxies BIOs to userspace Palmer Dabbelt
2020-12-03 21:58 ` [PATCH v1 4/5] selftests/dm-user: A handful of tests for dm-user Palmer Dabbelt
2020-12-03 21:58 ` [PATCH v1 5/5] MAINTAINERS: Add myself as a dm-user maintainer Palmer Dabbelt
2020-12-04 10:33 ` [PATCH v1 0/5] dm: dm-user: New target that proxies BIOs to userspace Christoph Hellwig
2020-12-07 18:55 ` Palmer Dabbelt
2020-12-10 3:38 ` [dm-devel] " Bart Van Assche
2020-12-10 17:03 ` Josef Bacik
2020-12-15 3:00 ` Palmer Dabbelt
2020-12-16 18:24 ` Vitaly Mayatskih
2020-12-17 6:55 ` Palmer Dabbelt
2020-12-22 13:32 ` Christoph Hellwig
2020-12-22 14:36 ` Mike Snitzer [this message]
2020-12-22 20:38 ` Palmer Dabbelt
2020-12-23 7:48 ` Christoph Hellwig
2020-12-23 16:59 ` Bart Van Assche
2020-12-22 20:31 ` [dm-devel] " Palmer Dabbelt
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