From 5b88a17cfdeba75e0092bab2c79aaf7d9e7db482 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 28 Feb 2019 11:00:18 -0500 Subject: [PATCH] block: optimize bvec iteration in bvec_iter_advance There is no need to only iterate in chunks of PAGE_SIZE or less in bvec_iter_advance, given that the callers pass in the chunk length that they are operating on - either that already is less than PAGE_SIZE because they do classic page-based iteration, or it is larger because the caller operates on multi-page bvecs. This should help shaving off a few cycles of the I/O hot path. Reviewed-by: Johannes Thumshirn Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe --- include/linux/bvec.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/include/linux/bvec.h b/include/linux/bvec.h index 87e82e503a52..f6275c4da13a 100644 --- a/include/linux/bvec.h +++ b/include/linux/bvec.h @@ -112,14 +112,15 @@ static inline bool bvec_iter_advance(const struct bio_vec *bv, } while (bytes) { - unsigned iter_len = bvec_iter_len(bv, *iter); - unsigned len = min(bytes, iter_len); + const struct bio_vec *cur = bv + iter->bi_idx; + unsigned len = min3(bytes, iter->bi_size, + cur->bv_len - iter->bi_bvec_done); bytes -= len; iter->bi_size -= len; iter->bi_bvec_done += len; - if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) { + if (iter->bi_bvec_done == cur->bv_len) { iter->bi_bvec_done = 0; iter->bi_idx++; }