Craig James wrote:
This data is good enough for what I'm doing. There were
reports from non-RAID users that the I/O scheduling could
make as much as a 4x difference in performance (which makes
sense for non-RAID), but these tests show me that three of
the four I/O schedulers are within
On Tue, 6 May 2008, Craig James wrote:
I/O Sched AVG Test1 Test2
--- -
cfq705 695715
noop 758 769747
deadline 741 705775
anticipatory 494 477511
Interesting. That contrasts with some tests I
On May 5, 2008, at 7:33 PM, Craig James wrote:
I had the opportunity to do more testing on another new server to
see whether the kernel's I/O scheduling makes any difference.
Conclusion: On a battery-backed RAID 10 system, the kernel's I/O
scheduling algorithm has no effect. This makes
Greg Smith wrote:
On Mon, 5 May 2008, Craig James wrote:
pgbench -i -s 20 -U test
That's way too low to expect you'll see a difference in I/O schedulers.
A scale of 20 is giving you a 320MB database, you can fit the whole
thing in RAM and almost all of it on your controller cache. What's
On Tue, 6 May 2008, Craig James wrote:
I only did two runs of each, which took about 24 minutes. Like the first
round of tests, the noise in the measurements (about 10%) exceeds the
difference between scheduler-algorithm performance, except that
anticipatory seems to be measurably slower.
Greg Smith wrote:
On Tue, 6 May 2008, Craig James wrote:
I only did two runs of each, which took about 24 minutes. Like the
first round of tests, the noise in the measurements (about 10%)
exceeds the difference between scheduler-algorithm performance, except
that anticipatory seems to be
On Mon, May 5, 2008 at 5:33 PM, Craig James [EMAIL PROTECTED] wrote:
(It also reinforces what the pgbench man page says: Short runs aren't
useful. Even these two-minute runs have a lot of variability. Before I
turned off AutoVacuum, the variability was more like 50% between runs.)
I'd
On Mon, 5 May 2008, Craig James wrote:
pgbench -i -s 20 -U test
That's way too low to expect you'll see a difference in I/O schedulers.
A scale of 20 is giving you a 320MB database, you can fit the whole thing
in RAM and almost all of it on your controller cache. What's there to
schedule?
