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| author | Jan Kara <jack@suse.cz> | 2017-09-06 16:21:24 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-09-06 17:27:26 -0700 |
| commit | c10f778ddfc161f5c58a8d6de4ad92235ea2eeba (patch) | |
| tree | 703158abaa22046480a5abc7591a67ec7c18f8ed /fs | |
| parent | b947cee4b96306037e166ff1ea5156c0ecdd7d91 (diff) | |
| download | linux-c10f778ddfc161f5c58a8d6de4ad92235ea2eeba.tar.bz2 | |
fs: fix performance regression in clean_bdev_aliases()
Commit e64855c6cfaa ("fs: Add helper to clean bdev aliases under a bh
and use it") added a wrapper for clean_bdev_aliases() that invalidates
bdev aliases underlying a single buffer head.
However this has caused a performance regression for bonnie++ benchmark
on ext4 filesystem when delayed allocation is turned off (ext3 mode) -
average of 3 runs:
Hmean SeqOut Char 164787.55 ( 0.00%) 107189.06 (-34.95%)
Hmean SeqOut Block 219883.89 ( 0.00%) 168870.32 (-23.20%)
The reason for this regression is that clean_bdev_aliases() is slower
when called for a single block because pagevec_lookup() it uses will end
up iterating through the radix tree until it finds a page (which may
take a while) but we are only interested whether there's a page at a
particular index.
Fix the problem by using pagevec_lookup_range() instead which avoids the
needless iteration.
Fixes: e64855c6cfaa ("fs: Add helper to clean bdev aliases under a bh and use it")
Link: http://lkml.kernel.org/r/20170726114704.7626-5-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/buffer.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index 5b20893708e2..7e531bb356bd 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1627,19 +1627,18 @@ void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len) struct pagevec pvec; pgoff_t index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); pgoff_t end; - int i; + int i, count; struct buffer_head *bh; struct buffer_head *head; end = (block + len - 1) >> (PAGE_SHIFT - bd_inode->i_blkbits); pagevec_init(&pvec, 0); - while (index <= end && pagevec_lookup(&pvec, bd_mapping, &index, - min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) { - for (i = 0; i < pagevec_count(&pvec); i++) { + while (pagevec_lookup_range(&pvec, bd_mapping, &index, end, + PAGEVEC_SIZE)) { + count = pagevec_count(&pvec); + for (i = 0; i < count; i++) { struct page *page = pvec.pages[i]; - if (page->index > end) - break; if (!page_has_buffers(page)) continue; /* @@ -1669,6 +1668,9 @@ unlock_page: } pagevec_release(&pvec); cond_resched(); + /* End of range already reached? */ + if (index > end || !index) + break; } } EXPORT_SYMBOL(clean_bdev_aliases); |