Re: xfs cgroup writeback support

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Mon, Jun 24, 2019 at 03:43:13PM +0200, Christoph Hellwig wrote:
> Hi all,
> 
> this small series adds cgroup writeback support to XFS.  Unlike
> the previous iteration of the support a few years ago it also
> ensures that that trailing bios in an ioend inherit the right
> cgroup.  It has been tested with the shared/011 xfstests test
> that was written to test this functionality in all file systems,
> and manually by Stefan Priebe.
> 
> This work was funded by Profihost AG.
> 
> Note that the first patch was also in my series to move the xfs
> writepage code to iomap.c and the second one will conflict with
> it.  We'll need to sort out which series to merge first, but given
> how simple this one I would suggest to go for this one.

By the way, did all the things Dave complained about in last year's
attempt[1] to add cgroup writeback support get fixed?  IIRC someone
whose name I didn't recognise complained about log starvation due to
REQ_META bios being charged to the wrong cgroup and other misbehavior.

Also, I remember that in the earlier 2017 discussion[2] we talked about
a fstest to test that writeback throttling actually capped bandwidth
usage correctly.  I haven't been following cgroupwb development since
2017 -- does it not ratelimit bandwidth now, or is there some test for
that?  The only test I could find was shared/011 which only tests the
accounting, not bandwidth.

--D

[1] https://patchwork.kernel.org/comment/21658249/
[2] https://patchwork.kernel.org/comment/21042703/