On Fri, Nov 08, 2019 at 02:41:27PM -0500, Josef Bacik wrote: > On Wed, Oct 23, 2019 at 06:53:08PM -0400, Dennis Zhou wrote: > > Provide an ability to rate limit based on mbps in addition to the iops > > delay calculated from number of discardable extents. > > I'm sort of confused, are we hiding the ability to set the iops limit and bps > limit behind BTRFS_DEBUG for a reason? IMHO the iops and ratelimiting should tune itself and no extra knobs should be necessary because this depends on the underlying devices and current load. The user set parameters can be wrong the moment it's done. Before we find the right way to tune it, the sysfs knobs are there to make it easy for someobody familiar with the internals of the async discard working to experiment. If we'd still want something for regular users, I'd suggest to add some sort of high-level strategies, like bursty/batched/conservative/slow/idk. But this would anyway build on existing default behaviour.
