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From: Pavel Begunkov <[email protected]>
To: [email protected]
Cc: Jens Axboe <[email protected]>,
	Christoph Hellwig <[email protected]>,
	Matthew Wilcox <[email protected]>,
	Ming Lei <[email protected]>,
	Johannes Weiner <[email protected]>,
	Alexander Viro <[email protected]>,
	"Darrick J . Wong" <[email protected]>,
	"Martin K . Petersen" <[email protected]>,
	Jonathan Corbet <[email protected]>,
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected]
Subject: [PATCH v1 2/6] iov_iter: optimise bvec iov_iter_advance()
Date: Tue, 15 Dec 2020 00:20:21 +0000	[thread overview]
Message-ID: <5c9c22dbeecad883ca29b31896c262a8d2a77132.1607976425.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>

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 <[email protected]>
---
 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


  parent reply	other threads:[~2020-12-15  0:25 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-15  0:20 [PATCH v1 0/6] no-copy bvec Pavel Begunkov
2020-12-15  0:20 ` [PATCH v1 1/6] target/file: allocate the bvec array as part of struct target_core_file_cmd Pavel Begunkov
2020-12-15  0:20 ` Pavel Begunkov [this message]
2020-12-15  9:37   ` [PATCH v1 2/6] iov_iter: optimise bvec iov_iter_advance() David Laight
2020-12-15 11:23     ` Pavel Begunkov
2020-12-15 13:54       ` David Laight
2020-12-15 13:56         ` Pavel Begunkov
2020-12-22 14:03   ` Christoph Hellwig
2020-12-15  0:20 ` [PATCH v1 3/6] bio: deduplicate adding a page into bio Pavel Begunkov
2020-12-22 14:04   ` Christoph Hellwig
2020-12-15  0:20 ` [PATCH v1 4/6] block/psi: remove PSI annotations from direct IO Pavel Begunkov
2020-12-15  0:56   ` Dave Chinner
2020-12-15  1:03     ` Pavel Begunkov
2020-12-15  1:33       ` Dave Chinner
2020-12-15 11:41         ` Pavel Begunkov
2020-12-22 14:07   ` Christoph Hellwig
2020-12-15  0:20 ` [PATCH v1 5/6] bio: add a helper calculating nr segments to alloc Pavel Begunkov
2020-12-15  1:00   ` Dave Chinner
2020-12-15  1:07     ` Pavel Begunkov
2020-12-15  1:09     ` Dave Chinner
2020-12-22 14:07   ` Christoph Hellwig
2020-12-15  0:20 ` [PATCH v1 6/6] block/iomap: don't copy bvec for direct IO Pavel Begunkov
2020-12-15  1:09   ` Dave Chinner
2020-12-15  1:15     ` Pavel Begunkov
2020-12-22 14:15   ` Christoph Hellwig
2020-12-15  1:41 ` [PATCH v1 0/6] no-copy bvec Ming Lei
2020-12-15 11:14   ` Pavel Begunkov
2020-12-15 12:03     ` Ming Lei
2020-12-15 14:05       ` Pavel Begunkov
2020-12-22 14:11         ` Christoph Hellwig
2020-12-23 12:52           ` Pavel Begunkov
2020-12-23 15:51             ` Christoph Hellwig
2020-12-23 16:04               ` James Bottomley
2020-12-23 20:23                 ` Douglas Gilbert
2020-12-23 20:32                   ` Pavel Begunkov
2020-12-24  6:41                     ` Christoph Hellwig
2020-12-24 16:45                       ` Douglas Gilbert
2020-12-24 17:30                   ` James Bottomley

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