On 7/19/24 11:43 AM, Petr Vorel wrote: > Hi all, > > LTP AIO DIO tests aiodio_sparse.c [1] and dio_sparse.c [2] (using [3]) slowed > down on kernel 6.6 on Btrfs and XFS, when run with default parameters. These > tests create 100 MB sparse file and write zeros (using libaio or O_DIRECT) while > 16 other processes reads the buffer and check only zero is there. > > Runtime of this particular setup (i.e. 100 MB file) on Btrfs and XFS on the > same system slowed down 9x (6.5: ~1 min 6.6: ~9 min). Ext4 is not affected. > (Non default parameter creates much smaller file, thus the change is not that > obvious). > > Because the slowdown has been here for few kernel releases I suppose nobody > complained and the test is somehow artificial (nobody uses this in a real world). > But still it'd be good to double check the problem. I can bisect a particular > commit. > > Because 2 filesystems affected, could be "Improve asynchronous iomap DIO > performance" [4] block layer change somehow related? No, because that got disabled before release for unrelated reasons. Why don't you just bisect it, since you have a simple test case? -- Jens Axboe
