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Message-Id: <5c9c22dbeecad883ca29b31896c262a8d2a77132.1607976425.git.asml.silence@gmail.com>
Date: Tue, 15 Dec 2020 00:20:21 +0000
From: Pavel Begunkov <asml.silence@...il.com>
To: linux-block@...r.kernel.org
Cc: Jens Axboe <axboe@...nel.dk>,
Christoph Hellwig <hch@...radead.org>,
Matthew Wilcox <willy@...radead.org>,
Ming Lei <ming.lei@...hat.com>,
Johannes Weiner <hannes@...xchg.org>,
Alexander Viro <viro@...iv.linux.org.uk>,
"Darrick J . Wong" <darrick.wong@...cle.com>,
"Martin K . Petersen" <martin.petersen@...cle.com>,
Jonathan Corbet <corbet@....net>, linux-xfs@...r.kernel.org,
linux-fsdevel@...r.kernel.org, io-uring@...r.kernel.org,
linux-kernel@...r.kernel.org, target-devel@...r.kernel.org,
linux-scsi@...r.kernel.org, linux-doc@...r.kernel.org
Subject: [PATCH v1 2/6] iov_iter: optimise bvec iov_iter_advance()
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@...il.com>
---
lib/iov_iter.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 1635111c5bd2..5b186dc2c9ea 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1067,6 +1067,21 @@ static void pipe_advance(struct iov_iter *i, size_t size)
pipe_truncate(i);
}
+static void iov_iter_bvec_advance(struct iov_iter *i, size_t size)
+{
+ 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;
+}
+
void iov_iter_advance(struct iov_iter *i, size_t size)
{
if (unlikely(iov_iter_is_pipe(i))) {
@@ -1077,6 +1092,10 @@ void iov_iter_advance(struct iov_iter *i, size_t size)
i->count -= size;
return;
}
+ if (iov_iter_is_bvec(i)) {
+ iov_iter_bvec_advance(i, size);
+ return;
+ }
iterate_and_advance(i, size, v, 0, 0, 0)
}
EXPORT_SYMBOL(iov_iter_advance);
--
2.24.0
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