Date: Fri, 12 Oct 2001 14:57:17 -0700 (PDT) From: Matthew Jacob <mjacob@feral.com> To: Jay Rossiter <jrossiter@symantec.com> Cc: <freebsd-hackers@FreeBSD.ORG> Subject: Re: Severe I/O Problems Message-ID: <20011012145533.C73308-100000@wonky.feral.com> In-Reply-To: <OF771AB257.5E1F2BC6-ON88256AE3.0077DC3F@symantec.com>
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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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