Date: Fri, 12 Oct 2001 15:26:07 -0700 (PDT) From: Matthew Jacob <mjacob@feral.com> To: Jay Rossiter <jrossiter@symantec.com>, <sos@freebsd.org>, Jordan Hubbard <jkh@freebsd.org> Cc: <freebsd-hackers@freebsd.org> Subject: Re: Severe I/O Problems Message-ID: <20011012152458.E73308-100000@wonky.feral.com> In-Reply-To: <OF93C7F686.4FAB3595-ON88256AE3.007A49DB@symantec.com>
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Interesting. If this bears out, what this tells me is that in some cases enabling write cacheing on ATAs is good, but in other cases, bad (probably provides interference effects). Soren? Jordan? -matt On Fri, 12 Oct 2001, Jay Rossiter wrote: > > > 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. > > > > > > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > > with "unsubscribe freebsd-hackers" in the body of the message > > > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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