Messages in this thread | | | Date | Thu, 3 Dec 2020 09:14:06 +0000 | From | Christoph Hellwig <> | Subject | Re: [PATCH] iov_iter: optimise bvec iov_iter_advance() |
| |
> @@ -1077,6 +1077,20 @@ void iov_iter_advance(struct iov_iter *i, size_t size) > i->count -= size; > return; > } > + if (iov_iter_is_bvec(i)) { > + struct bvec_iter bi; > + > + bi.bi_size = i->count; > + bi.bi_bvec_done = i->iov_offset; > + bi.bi_idx = 0; > + bvec_iter_advance(i->bvec, &bi, size); > + > + i->bvec += bi.bi_idx; > + i->nr_segs -= bi.bi_idx; > + i->count = bi.bi_size; > + i->iov_offset = bi.bi_bvec_done; > + return; > + } > iterate_and_advance(i, size, v, 0, 0, 0)
I like the idea, but whu not avoid the on-stack bvec_iter and just open code this entirely using a new helper? E.g.
static void bio_iov_iter_advance(struct iov_iter *i, size_t bytes) { unsigned int cnt;
i->count -= bytes;
bytes += i->iov_offset; for (cnt = 0; bytes && bytes >= i->bvec[cnt].bv_len; cnt++) bytes -= i->bvec[cnt].bv_len; i->iov_offset = bytes;
i->bvec += cnt; i->nr_segs -= cnt; }
| |