Date: Wed, 08 Nov 2000 20:11:30 -0500 From: "Simon" <simon@optinet.com> To: "Brian Behlendorf" <brian@collab.net>, "stable@freebsd.org" <stable@freebsd.org> Subject: Re: disk I/O Message-ID: <20001109010655.89B7037B4CF@hub.freebsd.org> In-Reply-To: <Pine.BSF.4.21.0011081625011.1844-100000@yez.hyperreal.org>
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Is that machine using any swap when this happens? If so, that's most likely why. It tries to spawn processes, but can't do it fast enough. It happens on my box now and then. Running 4.1-R -Simon On Wed, 8 Nov 2000 16:35:13 -0800 (PST), Brian Behlendorf wrote: > >RELENG_4, kernel last updated & built Aug 31st, so apologies if this >touches a problem that was fixed since then. I'd be happy to upgrade >after 4.2-RELEASE goes out if people think there was a fix applied >for this. > >I'm having agonizingly slow disk I/O. Granted, this is a heavily pounded >machine (~2M web hits/day with ~50K being CGI or java, 500K mail >deliveries using qmail, lots of CVS accesses) yet I get spikes in the load >going up to 200 at times, during which the machine's largely frozen to >shell access & other services are much slower. It always comes back (go >freebsd!) but it still feels like I/O is the culprit. The CPU almost >always has idle time available, yet during the day even doing an "ls" in a >moderately sized dir is slow. Here's iostat 5: > > tty da0 da1 acd0 cpu > tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id > 2 59 0.00 0 0.00 0.00 0 0.00 0.00 0 0.00 23 3 14 3 55 > 0 171 4.45 91 0.40 9.62 118 1.11 0.00 0 0.00 65 0 27 7 0 > 0 633 5.81 110 0.62 10.38 142 1.44 0.00 0 0.00 50 0 24 4 21 > 0 435 4.00 85 0.33 6.90 157 1.06 0.00 0 0.00 73 0 18 5 4 > 0 635 4.25 91 0.38 8.80 101 0.87 0.00 0 0.00 74 0 22 4 0 > 0 495 4.36 92 0.39 7.67 156 1.17 0.00 0 0.00 60 0 37 3 0 > 0 450 4.39 95 0.41 8.58 147 1.23 0.00 0 0.00 56 0 27 4 13 > 0 254 5.15 90 0.45 7.38 170 1.23 0.00 0 0.00 5 0 8 3 83 > 0 530 4.21 83 0.34 7.99 171 1.33 0.00 0 0.00 8 0 15 3 74 > 0 502 4.13 93 0.37 7.17 169 1.19 0.00 0 0.00 21 0 16 5 58 > >relevant dmesg output: > >sym0: <895> port 0x9000-0x90ff mem 0xfa201000-0xfa201fff,0xfa202000-0xfa2020ff irq 10 at device 4.0 on pci1 >sym0: Symbios NVRAM, ID 7, Fast-40, LVD, parity checking >sym0: open drain IRQ line driver, using on-chip SRAM >sym0: using LOAD/STORE-based firmware. >da1 at sym0 bus 0 target 1 lun 0 >da1: <IBM DMVS18D 0077> Fixed Direct Access SCSI-3 device >da1: 80.000MB/s transfers (40.000MHz, offset 31, 16bit), Tagged Queueing Enabled >da1: 17501MB (35843670 512 byte sectors: 255H 63S/T 2231C) >da0 at sym0 bus 0 target 0 lun 0 >da0: <HP 18.2GB A 80-B001 B001> Fixed Direct Access SCSI-2 device >da0: 80.000MB/s transfers (40.000MHz, offset 15, 16bit), Tagged Queueing Enabled >da0: 17366MB (35566480 512 byte sectors: 255H 63S/T 2213C) > >Ideas? This is actually during a more lightly loaded time period. It >just "feels" like I should be able to push more than 80-100 tps through >da0 (lots of small writes and fsyncs, admittedly) and more than 150tps on >da1 (which is almost all reads). Anything else I should be looking at? > > Brian > > > > > >To Unsubscribe: send mail to majordomo@FreeBSD.org >with "unsubscribe freebsd-stable" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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