Justin Piszcz wrote:
# echo 3 > /proc/sys/vm/drop_caches
# dd if=/dev/md3 of=/dev/null bs=1M count=10240
10240+0 records in
10240+0 records out
10737418240 bytes (11 GB) copied, 399.352 seconds, 26.9 MB/s
# for i in sde sdg sdi sdk; do echo 192 >
/sys/block/"$i"/queue/max_sectors_kb; echo "Set
/sys/block/"$i"/queue/max_sectors_kb to 192kb"; done
Set /sys/block/sde/queue/max_sectors_kb to 192kb
Set /sys/block/sdg/queue/max_sectors_kb to 192kb
Set /sys/block/sdi/queue/max_sectors_kb to 192kb
Set /sys/block/sdk/queue/max_sectors_kb to 192kb
# echo 3 > /proc/sys/vm/drop_caches
# dd if=/dev/md3 of=/dev/null bs=1M count=10240
10240+0 records in
10240+0 records out
10737418240 bytes (11 GB) copied, 398.069 seconds, 27.0 MB/s
Awful performance with your numbers/drop_caches settings.. !
What were your tests designed to show?
To start, I expect then to show change in write, not read... and IIRC (I
didn't look it up) drop_caches just flushes the caches so you start with
known memory contents, none.
Justin.
On Fri, 12 Jan 2007, Justin Piszcz wrote:
On Fri, 12 Jan 2007, Al Boldi wrote:
Justin Piszcz wrote:
RAID 5 TWEAKED: 1:06.41 elapsed @ 60% CPU
This should be 1:14 not 1:06(was with a similarly sized file but not the
same) the 1:14 is the same file as used with the other benchmarks. and to
get that I used 256mb read-ahead and 16384 stripe size ++ 128
max_sectors_kb (same size as my sw raid5 chunk size)
max_sectors_kb is probably your key. On my system I get twice the read
performance by just reducing max_sectors_kb from default 512 to 192.
Can you do a fresh reboot to shell and then:
$ cat /sys/block/hda/queue/*
$ cat /proc/meminfo
$ echo 3 > /proc/sys/vm/drop_caches
$ dd if=/dev/hda of=/dev/null bs=1M count=10240
$ echo 192 > /sys/block/hda/queue/max_sectors_kb
$ echo 3 > /proc/sys/vm/drop_caches
$ dd if=/dev/hda of=/dev/null bs=1M count=10240
--
bill davidsen <davidsen@xxxxxxx>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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