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Message-Id: <20170601093245.29238-9-jack@suse.cz> Date: Thu, 1 Jun 2017 11:32:18 +0200 From: Jan Kara <jack@...e.cz> To: <linux-mm@...ck.org> Cc: Hugh Dickins <hughd@...gle.com>, David Howells <dhowells@...hat.com>, linux-afs@...ts.infradead.org, Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>, linux-nilfs@...r.kernel.org, Bob Peterson <rpeterso@...hat.com>, cluster-devel@...hat.com, Jaegeuk Kim <jaegeuk@...nel.org>, linux-f2fs-devel@...ts.sourceforge.net, tytso@....edu, linux-ext4@...r.kernel.org, Ilya Dryomov <idryomov@...il.com>, "Yan, Zheng" <zyan@...hat.com>, ceph-devel@...r.kernel.org, linux-btrfs@...r.kernel.org, David Sterba <dsterba@...e.com>, "Darrick J . Wong" <darrick.wong@...cle.com>, linux-xfs@...r.kernel.org, Nadia Yvette Chambers <nyc@...omorphy.com>, Jan Kara <jack@...e.cz> Subject: [PATCH 08/35] 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: e64855c6cfaa0a80c1b71c5f647cb792dc436668 Signed-off-by: Jan Kara <jack@...e.cz> --- fs/buffer.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index fe0ee01c5a44..d63b22e50f38 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1632,19 +1632,18 @@ 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; /* @@ -1674,6 +1673,9 @@ void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len) } pagevec_release(&pvec); cond_resched(); + /* End of range already reached? */ + if (index > end || !index) + break; } } EXPORT_SYMBOL(clean_bdev_aliases); -- 2.12.3
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