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. -- Jens Axboe
