On Tue, 2006-01-10 at 21:25 -0800, Andrew Morton wrote:
> Mingming Cao <[email protected]> wrote:
> >
> > Tests done so far includes fsx,tiobench and dbench. The following
> > numbers collected from Direct IO tests (1G file creation/read) shows
> > the system time have been greatly reduced (more than 50% on my 8 cpu
> > system) with the patches.
> >
> > 1G file DIO write:
> > 2.6.15 2.6.15+patches
> > real 0m31.275s 0m31.161s
> > user 0m0.000s 0m0.000s
> > sys 0m3.384s 0m0.564s
> >
> >
> > 1G file DIO read:
> > 2.6.15 2.6.15+patches
> > real 0m30.733s 0m30.624s
> > user 0m0.000s 0m0.004s
> > sys 0m0.748s 0m0.380s
> >
> > Some previous test we did on buffered IO with using multiple blocks
> > allocation and delayed allocation shows noticeable improvement on
> > throughput and system time.
>
> I'd be interested in seeing benchmark results for the common
> allocate-one-block case - just normal old buffered IO without any
> additional multiblock patches. Would they show any regression?
>
Hi Andrew,
One thing I want to clarify is that: for the buffered IO, even with
mutlipleblock patches, currently ext3 is still allocate one block at a
time.(we will need delayed allocation to make use of the multiple block
allocation)
I did the same test on buffered IO, w/o the patches. Very little
regression(less than 1% could be consider as noise) comparing 2.6.15
kernel w/o patches:
buffered IO write: (no sync)
# time ./filetst -b 1048576 -w -f /mnt/a
2.6.15 2.6.15+patches
real 0m25.773s 0m26.102s
user 0m0.004s 0m0.000s
sys 0m15.065s 0m16.053s
buffered IO read (after umount/remount)
# time ./filetst -b 1048576 -r -f /mnt/a
2.6.15 2.6.15+patches
real 0m29.257s 0m29.257s
user 0m0.000s 0m0.000s
sys 0m6.996s 0m6.980s
But I do notice regression between vanilla 2.6.14 kernel and vanilla
2.6.15 kernel on buffered IO(about 18%).
# time ./filetst -b 1048576 -w -f /mnt/a
2.6.14 2.6.15
real 0m21.710s 0m25.773s
user 0m0.012s 0m0.004s
sys 0m14.569s 0m15.065s
I also found tiobench(sequential write test) and dbench has similar
regression between 2.6.14 and 2.6.15. Actually I found 2.6.15 rc2
already has the regression. Is this a known issue? Anyway I will
continue looking at the issue...
Thanks,
Mingming
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