Date: Fri, 12 Oct 2001 15:19:23 -0700 From: "Jay Rossiter" <jrossiter@symantec.com> To: <mjacob@feral.com> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Severe I/O Problems Message-ID: <OF93C7F686.4FAB3595-ON88256AE3.007A49DB@symantec.com>
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This does seem to be doing some good. The beginning of the test run
is hovering ~30% CPU. I'll have to wait until it finished before I can
see if it effected the overall time, though.
Something else that I forgot to mention, is that yesterday I did a
profiled run, and the code-time between the two scenarios differs by less
than ten minutes. (The in-memory files vs. on disk files) The disk files
just take infinitely longer to do anything to.
Matthew Jacob
<mjacob@feral. To: Jay Rossiter <jrossiter@symantec.com>
com> cc: <freebsd-hackers@FreeBSD.ORG>
Subject: Re: Severe I/O Problems
10/12/2001
02:57 PM
Please respond
to mjacob
Hmm. Interesting. What's the state of the ATA write caching bit?
(sysctl hw.ata.wc)?
If it is set to 1, try setting it to 0 in /boot/loader.conf
(e.g., add
hw.ata.wc=0
)
to /boot/loader.conf
-matt
On Fri, 12 Oct 2001, Jay Rossiter wrote:
>
> Someone on -questions recommended that I forward this over here for
> you guys to look at. (I'm not subbed to this list)
>
> There appear to be a lot of changes that went into the filesystem and I/O
> code between 4.3 and 4.4. A little over a week ago I upgraded my 4.3 box
> to 4.4-STABLE and immediately I started having I/O slowdown. I do
> development and QA on a program that is very I/O bound, but the changes
> between 4.3 and 4.4 aren't small enough that I can ignore them.
>
> A few statistics:
>
> BSD, P4 1.4GHz, ATA100 drives
> - Normal test run on 4.3 was taking ~3 hours.
> - Normal test run on 4.4 is taking 15-16 hours.
>
> P3-800, ATA66 drives, SuSE Linux 7.1:
> - Normal test run takes ~4.5 hours.
>
> UltraSparc 10, Solaris 8, ATA66 drives:
> - Normal test run takes ~6 hours.
>
> As you can see, this jump was just phenomenal.
>
> I can run these tests on a custom 'ramdrive' and the test run takes 1.5
> hours on BSD. ~4 on Solaris, ~2.5 on Linux.
>
> Even the RS/6000 I test AIX 4.3 with doesn't take this long, though I
don't
> have statistics for it.
>
> It appears that the app gets stuck switching between the getblk and biowr
> states in top and ps, and very rarely does it take more than 5% of the
CPU.
> On all other OS's, and even on 4.3, this app was pegging the CPU while it
> did its work.
>
> Basically.. this all comes down to "What the hell is going on here?!" and
> "Are there plans to fix it and did anyone even know there was a problem?"
>
> ---
> Jay Rossiter 503-614-7917
> QA Engineer, Test Lead
> Symantec Corp.
>
>
>
>
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