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Subject[PATCH] iov_iter: optimise bvec iov_iter_advance()
Date
iov_iter_advance() is heavily used, but implemented through generic
iteration. As bvecs have a specifically crafted advance() function, i.e.
bvec_iter_advance(), which is faster and slimmer, use it instead.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
lib/iov_iter.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 1635111c5bd2..7fbdd9ef3ff0 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -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)
}
EXPORT_SYMBOL(iov_iter_advance);
--
2.24.0
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