On 4/15/23 11:54?PM, Christoph Hellwig wrote: > On Fri, Apr 14, 2023 at 08:36:12AM -0700, Darrick J. Wong wrote: >> IIUC uring wants to avoid the situation where someone sends 300 writes >> to the same file, all of which end up in background workers, and all of >> which then contend on exclusive i_rwsem. Hence it has some hashing >> scheme that executes io requests serially if they hash to the same value >> (which iirc is the inode number?) to prevent resource waste. >> >> This flag turns off that hashing behavior on the assumption that each of >> those 300 writes won't serialize on the other 299 writes, hence it's ok >> to start up 300 workers. >> >> (apologies for precoffee garbled response) > > It might be useful if someone (Jens?) could clearly document the > assumptions for this flag. I guess it can be summed up as the common case should not be using exclusive (per file/inode) locking. If file extensions need exclusive locking that's less of a concern, as I don't think it's unreasonable to expect that to require stricter locking. -- Jens Axboe
