Hi,
I introduced "is_partially_uptodate" aops for NILFS2.
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=16 --max-requests=200000 --test=fileio --file-num=
1 --file-block-size=8K --file-total-size=2G --file-test-mode=rndrw
--file-fsync-freq=0 --fil
e-rw-ratio=1 run
-2.6.30-rc5
Test execution summary:
total time: 151.2907s
total number of events: 200000
total time taken by event execution: 2409.8387
per-request statistics:
min: 0.0000s
avg: 0.0120s
max: 0.9306s
approx. 95 percentile: 0.0439s
Threads fairness:
events (avg/stddev): 12500.0000/238.52
execution time (avg/stddev): 150.6149/0.01
-2.6.30-rc5-patched
Test execution summary:
total time: 140.8828s
total number of events: 200000
total time taken by event execution: 2240.8577
per-request statistics:
min: 0.0000s
avg: 0.0112s
max: 0.8750s
approx. 95 percentile: 0.0418s
Threads fairness:
events (avg/stddev): 12500.0000/218.43
execution time (avg/stddev): 140.0536/0.01
arch: ia64
pagesize: 16k
Thanks.
Signed-off-by: Hisashi Hifumi <[email protected]>
diff -Nrup linux-2.6.30-rc5.org/fs/nilfs2/inode.c
linux-2.6.30-rc5.nilfs/fs/nilfs2/inode.c
--- linux-2.6.30-rc5.org/fs/nilfs2/inode.c 2009-05-11 10:07:15.000000000
+0900
+++ linux-2.6.30-rc5.nilfs/fs/nilfs2/inode.c 2009-05-12 10:22:50.000000000
+0900
@@ -249,6 +249,7 @@ struct address_space_operations nilfs_ao
/* .releasepage = nilfs_releasepage, */
.invalidatepage = block_invalidatepage,
.direct_IO = nilfs_direct_IO,
+ .is_partially_uptodate = block_is_partially_uptodate,
};
struct inode *nilfs_new_inode(struct inode *dir, int mode)
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