Re: [PATCHSET 0/2] sync discard

Christoph Hellwig
2018-05-02T12:45:08Z

On Mon, Apr 30, 2018 at 09:32:50AM -0600, Jens Axboe wrote:
> We recently had a pretty severe perf regression with the XFS async
> discard. This small series add a SYNC issue discard flag, and also
> limits the chain size for sync discards. Patch 2 adds support for
> reverting XFS back to doign sync discards.

Please explain the hardware and workload that you see this with.
Also given that it is a hardware limitation a quirk limiting the
size of discard requests and/or number of outstanding discards
would be more useful than falling back to a broken mode of issueing
block commands.