From bddaafa11a549fff311bcf2e04bbfb5139812cb7 Mon Sep 17 00:00:00 2001 From: Hisashi Hifumi Date: Sun, 29 Mar 2009 09:53:38 +0200 Subject: xfs: pagecache usage optimization Hi. I introduced "is_partially_uptodate" aops for XFS. A page can have multiple buffers and even if a page is not uptodate, some buffers can be uptodate on pagesize != blocksize environment. This aops checks that all buffers which correspond to a part of a file that we want to read are uptodate. If so, we do not have to issue actual read IO to HDD even if a page is not uptodate because the portion we want to read are uptodate. "block_is_partially_uptodate" function is already used by ext2/3/4. With the following patch random read/write mixed workloads or random read after random write workloads can be optimized and we can get performance improvement. I did a performance test using the sysbench. #sysbench --num-threads=4 --max-requests=100000 --test=fileio --file-num=1 \ --file-block-size=8K --file-total-size=1G --file-test-mode=rndrw \ --file-fsync-freq=0 --file-rw-ratio=0.5 run -2.6.29-rc6 Test execution summary: total time: 123.8645s total number of events: 100000 total time taken by event execution: 442.4994 per-request statistics: min: 0.0000s avg: 0.0044s max: 0.3387s approx. 95 percentile: 0.0118s -2.6.29-rc6-patched Test execution summary: total time: 108.0757s total number of events: 100000 total time taken by event execution: 417.7505 per-request statistics: min: 0.0000s avg: 0.0042s max: 0.3217s approx. 95 percentile: 0.0118s arch: ia64 pagesize: 16k blocksize: 4k Signed-off-by: Hisashi Hifumi Reviewed-by: Christoph Hellwig Reviewed-by: Felix Blyakher --- fs/xfs/linux-2.6/xfs_aops.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c index de3a198f771e..c13f67300fe7 100644 --- a/fs/xfs/linux-2.6/xfs_aops.c +++ b/fs/xfs/linux-2.6/xfs_aops.c @@ -1623,4 +1623,5 @@ const struct address_space_operations xfs_address_space_operations = { .bmap = xfs_vm_bmap, .direct_IO = xfs_vm_direct_IO, .migratepage = buffer_migrate_page, + .is_partially_uptodate = block_is_partially_uptodate, }; -- cgit v1.2.3