The patch titled
readahead: move synchronous readahead call out of splice loop
has been added to the -mm tree. Its filename is
readahead-move-synchronous-readahead-call-out-of-splice-loop.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: readahead: move synchronous readahead call out of splice loop
From: Fengguang Wu <wfg@xxxxxxxxxxxxxxxx>
Move synchronous page_cache_readahead_ondemand() call out of splice loop.
This avoids one pointless page allocation/insertion in case of non-zero
ra_pages, or many pointless readahead calls in case of zero ra_pages.
Note that if a user sets ra_pages to less than PIPE_BUFFERS=16 pages, he will
not get expected readahead behavior anyway. The splice code works in batches
of 16 pages, which can be taken as another form of synchronous readahead.
Signed-off-by: Fengguang Wu <wfg@xxxxxxxxxxxxxxxx>
Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/splice.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff -puN fs/splice.c~readahead-move-synchronous-readahead-call-out-of-splice-loop fs/splice.c
--- a/fs/splice.c~readahead-move-synchronous-readahead-call-out-of-splice-loop
+++ a/fs/splice.c
@@ -299,12 +299,16 @@ __generic_file_splice_read(struct file *
* Lookup the (hopefully) full range of pages we need.
*/
spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages);
+ index += spd.nr_pages;
/*
* If find_get_pages_contig() returned fewer pages than we needed,
- * allocate the rest.
+ * readahead/allocate the rest.
*/
- index += spd.nr_pages;
+ if (spd.nr_pages < nr_pages)
+ page_cache_readahead_ondemand(mapping, &in->f_ra, in,
+ NULL, index, nr_pages - spd.nr_pages);
+
while (spd.nr_pages < nr_pages) {
/*
* Page could be there, find_get_pages_contig() breaks on
@@ -312,9 +316,6 @@ __generic_file_splice_read(struct file *
*/
page = find_get_page(mapping, index);
if (!page) {
- page_cache_readahead_ondemand(mapping, &in->f_ra, in,
- NULL, index, nr_pages - spd.nr_pages);
-
/*
* page didn't exist, allocate one.
*/
_
Patches currently in -mm which might be from wfg@xxxxxxxxxxxxxxxx are
readahead-introduce-pg_readahead.patch
readahead-add-look-ahead-support-to-__do_page_cache_readahead.patch
readahead-min_ra_pages-max_ra_pages-macros.patch
readahead-data-structure-and-routines.patch
readahead-on-demand-readahead-logic.patch
readahead-convert-filemap-invocations.patch
readahead-convert-splice-invocations.patch
readahead-convert-ext3-ext4-invocations.patch
readahead-remove-the-old-algorithm.patch
readahead-move-synchronous-readahead-call-out-of-splice-loop.patch
readahead-pass-real-splice-size.patch
mm-share-pg_readahead-and-pg_reclaim.patch
-
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