On 2023-04-24 00:45, Christoph Hellwig wrote: > On Thu, Apr 20, 2023 at 02:10:02PM -0600, Logan Gunthorpe wrote: >>> I am hoping to make raid5_make_request() a little faster for non-rotational >>> devices. We may not easily observe a difference in performance, but things >>> add up. Does this make sense? >> >> I guess. But without a performance test that shows that it makes an >> improvement, I'm hesitant about that. It could also be that it helps a >> tiny bit for non-rotational disks, but we just don't know. >> >> Unfortunately, I don't have the time right now to do these performance >> tests. > > FYI, SSDs in general do prefer sequential write streams. For most you > won't see a different in write performance itself, but it will help with > reducing GC overhead later on. Thanks. Yes, my colleague was able to run performance testing on this patch and didn't find any degradation with Jan's optimization turned on. So I don't think it's worth doing this only for rotational disks and Jan's original patch makes sense. Logan
