On 11/5/18 3:51 PM, Christoph Hellwig wrote: > On Mon, Nov 05, 2018 at 01:10:21PM -0500, Brian Foster wrote: >> When online discard is enabled, discards of busy extents are >> submitted asynchronously as a bio chain. bio completion and >> resulting busy extent cleanup is deferred to a workqueue. Async >> discard submission is intended to avoid blocking log forces on a >> full discard sequence which can take a noticeable amount of time in >> some cases. >> >> We've had reports of this still producing log force stalls with XFS >> on VDO, > > Please fix this in VDO instead. We should not work around out of > tree code making stupid decisions. Is there some downside to Brian's proposal, in principle? It seems like it would be an improvement for device that might cause a discard bottleneck like this. Thanks, -Eric
