On 09/12/2020 16:53, Jens Axboe wrote: > On 12/8/20 7:19 PM, Pavel Begunkov wrote: >> The idea is to avoid copying, merging, etc. bvec from iterator to bio >> in direct I/O and use the one we've already got. Hook it up for io_uring. >> Had an eye on it for a long, and it also was brought up by Matthew >> just recently. Let me know if I forgot or misplaced some tags. >> >> A benchmark got me 430KIOPS vs 540KIOPS, or +25% on bare metal. And perf >> shows that bio_iov_iter_get_pages() was taking ~20%. The test is pretty >> silly, but still imposing. I'll redo it closer to reality for next >> iteration, anyway need to double check some cases. >> >> If same applied to iomap, common chunck can be moved from block_dev >> into bio_iov_iter_get_pages(), but if there any benefit for filesystems, >> they should explicitly opt in with ITER_BVEC_FLAG_FIXED. > > Ran this on a real device, and I get a 10% bump in performance with it. > That's pretty amazing! So please do pursue this one and pull it to > completion. I'm curious, what block size did you use? -- Pavel Begunkov
