On Mon 04 Nov 2019 04:14:56 PM CET, Max Reitz wrote: >>> No, what I meant was that the original problem that led to >>> c8bb23cbdbe would go away. >> >> Ah, right. Not quite, according to my numbers: >> >> |--------------+----------------+-----------------+-------------| >> | Cluster size | subclusters=on | subclusters=off | fallocate() | >> |--------------+----------------+-----------------+-------------| >> | 256 KB | 10182 IOPS | 966 IOPS | 14007 IOPS | >> | 512 KB | 7919 IOPS | 563 IOPS | 13442 IOPS | >> | 1024 KB | 5050 IOPS | 465 IOPS | 13887 IOPS | >> | 2048 KB | 2465 IOPS | 271 IOPS | 13885 IOPS | >> |--------------+----------------+-----------------+-------------| >> >> There's obviously no backing image, and only the last column uses >> handle_alloc_space() / fallocate(). > > Thanks for providing some numbers! > > It was my impression, too, that subclusters wouldn’t solve it. But it > didn’t seem like that big of a difference to me. Did you run this > with aio=native? (Because that’s where we have the XFS problem)
Here's with aio=native |--------------+----------------+-----------------+-------------| | Cluster size | subclusters=on | subclusters=off | fallocate() | |--------------+----------------+-----------------+-------------| | 256 KB | 19897 IOPS | 891 IOPS | 32194 IOPS | | 512 KB | 17881 IOPS | 436 IOPS | 33092 IOPS | | 1024 KB | 17050 IOPS | 341 IOPS | 32768 IOPS | | 2048 KB | 7854 IOPS | 207 IOPS | 30944 IOPS | |--------------+----------------+-----------------+-------------| Berto
