Re: [RFC] changes to buffer.c (was Test12 ll_rw_block error)

Daniel Phillips
2000-12-28T16:22:19Z

Chris Mason wrote:
>
> On Wednesday, December 27, 2000 21:26:02 +0100 Daniel Phillips
> <phillips@innominate.de> wrote:
>
> > Hi Chris. I took your patch for a test drive under dbench and it seems
> > impressively stable under load, but there are performance problems.
> >
> > Test machine: 64 meg, 500 Mhz K6, IDE, Ext2, Blocksize=4K
> > Without patch: 9.5 MB/sec, 11 min 6 secs
> > With patch: 3.12 MB/sec, 33 min 51 sec
> >
>
> Cool, thanks for the testing. Which benchmark are you using? bonnie and
> dbench don't show any changes on my scsi disks, I'll give IDE a try as well.

Chris, this was an error, I had accidently booted the wrong kernel. The
'With patch' results above are for 2.2.16, not your patch.

With correct results you are looking much better:

Test machine: 64 meg, 500 Mhz K6, IDE, Ext2, Blocksize=4K
Test: dbench 48

pre13 without patch: 9.5 MB/sec 11 min 6 secs
pre13 with patch: 8.9 MB/sec 11 min 46 secs
2.2.16: 3.1 MB/sec 33 min 51 sec

This benchmark doesn't seem to suffer a lot from noise, so the 7%
slowdown with your patch likely real.

We've come a long way from 2.2.16, haven't we? I'll run some of these
tests against 2.2 pre19 kernels and maybe fan the flames of the 2.2/2.4
competition a little.

--
Daniel