|
I seemed to have missed this during the OSDI and end-of-term rush. I've implemented a couple of user-space block device components for research projects, so I thought I'd weigh in.
In particular, does this offer significant advantages over TCMU? It uses the UIO framework for a ring of SCSI requests to user space, and seems to be quite efficient. The differences seem to be:
(I'm actually really bummed that I didn't discover TCMU until recently, as I think we would have used it on a few research projects in the past.)
I have no idea whether you can hand things off to another process - I don't think the UIO framework would have any problems with that, so it probably
comes down to whether the target_core_user module would allow its memory region to be mapped by multiple processes.
I've got the world's quickest and dirtiest SCSI implementation that I've hacked up to use with TCMU, although the only real experimentation I've
done is by hacking tcmu-runner. I'd definitely be interested in talking to any people who are interested in this, to develop a proper SCSI library that would allow you to use TCMU outside of tcmu-runner.
From: Bart Van Assche <bvanassche@xxxxxxx>
Sent: Wednesday, December 9, 2020 10:38 PM To: Palmer Dabbelt <palmer@xxxxxxxxxxx>; Christoph Hellwig <hch@xxxxxxxxxxxxx> Cc: snitzer@xxxxxxxxxx <snitzer@xxxxxxxxxx>; linux-doc@xxxxxxxxxxxxxxx <linux-doc@xxxxxxxxxxxxxxx>; shuah@xxxxxxxxxx <shuah@xxxxxxxxxx>; corbet@xxxxxxx <corbet@xxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx <linux-kernel@xxxxxxxxxxxxxxx>; Josef Bacik <josef@xxxxxxxxxxxxxx>; linux-raid@xxxxxxxxxxxxxxx <linux-raid@xxxxxxxxxxxxxxx>; song@xxxxxxxxxx <song@xxxxxxxxxx>; dm-devel@xxxxxxxxxx <dm-devel@xxxxxxxxxx>; Mike Christie <michael.christie@xxxxxxxxxx>; linux-kselftest@xxxxxxxxxxxxxxx <linux-kselftest@xxxxxxxxxxxxxxx>; kernel-team@xxxxxxxxxxx <kernel-team@xxxxxxxxxxx>; agk@xxxxxxxxxx <agk@xxxxxxxxxx> Subject: Re: [PATCH v1 0/5] dm: dm-user: New target that proxies BIOs to userspace On 12/7/20 10:55 AM, Palmer Dabbelt wrote:
> All in all, I've found it a bit hard to figure out what sort of interest > people > have in dm-user: when I bring this up I seem to run into people who've done > similar things before and are vaguely interested, but certainly nobody is > chomping at the bit. I'm sending it out in this early state to try and > figure > out if it's interesting enough to keep going. Cc-ing Josef and Mike since their nbd contributions make me wonder whether this new driver could be useful to their use cases? Thanks, Bart. |
-- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
