Date: Thu, 09 Sep 2004 19:48:20 +0200 From: =?ISO-8859-1?Q?S=F8ren_Schmidt?= <sos@DeepCore.dk> To: Kevin Oberman <oberman@es.net> Cc: Bjoern Koenig <bkoenig@cs.tu-berlin.de> Subject: Re: poor ATA disk speed with ICH2 Message-ID: <41409764.4040708@DeepCore.dk> In-Reply-To: <20040909171404.CAC5B5D04@ptavv.es.net> References: <20040909171404.CAC5B5D04@ptavv.es.net>
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Kevin Oberman wrote: >>From: "Bjoern Koenig" <bkoenig@cs.tu-berlin.de> >>Date: Wed, 8 Sep 2004 12:29:03 +0200 >>Sender: owner-freebsd-current@freebsd.org >> >>Hello, >> >>first time I installed a beta of FreeBSD 5.3 I noticed very poor disk =3D= >>speed. >>I built a kernel without this whole debugging stuff; but it remains bad= =2E =3D >>I >>supposed that this issue depends on further debugging features which I >>didn't know. So I waited until UPDATING told that debugging options are= >>removed from kernel and userland. Now I built a new kernel again and th= e >>disk speed is still unacceptable. Is there any further debugging option= ? >> >>Some facts: >> >>FreeBSD 5.3-BETA3 without any debugging: >> per char write: 13.78 MB/s (32.7% CPU usage) >> block write: 13.97 MB/s (12.8%) >> per char read: 22.31 MB/s (45.2%) >> block read: 37.44 MB/s (14.8%) >> >>FreeBSD 4.10-STABLE: >> per char write: 37.29 MB/s (75.7%) >> block write: 36.91 MB/s (28.7%) >> per char read: 38.53 MB/s (80.4%) >> block read: 37.45 MB/s (10.9%) >> >>(tested with bonnie, atacontrol shows UDMA100 both) >> >>Controller: Intel 82801BA (ICH2) >>Hard disk: Seagate ST380021A >=20 >=20 > I had previously reported this. I did some testing with the assistance > of Robert Watson and it appears that the issue is ATA. The thread had a= > subject of "Disk performance under CURRENT" and was back in May. >=20 > I plotted out the times for various sizes of I/O and > the only real issue was with write. The per character speed should > increase fairly quickly with increased I/O size and did for V4 and for > reads. For writes, it started the same for short writes as these tend t= o > be CPU bound. But, for longer writes, the increase in speed is MUCH les= s > than it was with V4 write or for reads and throughput tops out at > between 16 and 32KB transfers at something far below what I saw in V4. >=20 > I was also hearing a LOT of disk seek operations that did not seem > appropriate to me. (I did the testing with dd(1) in single-user mode.) >=20 > FWIW, I did my tests on an IBM T30 which is a P4@1.8 GHz with ICH3 > support chips. >=20 > Looking back at the history in my e-mail archive, I'm not certain that > sos@ was copied. Ouch! Mea culpa! I fixed a chip setup problem on the ICH* chips some days ago, its has=20 been committed to RELENG_5 as well. However it would normally be=20 harmless if the BIOS has set the mode (which it normally does). Besides that, I know of no problems performance wise. Disk seek=20 operations during sequential access suggests that there is something=20 else going on simultanious to the test as the driver doesn't issue seeks = without being asked to from the system. -S=F8ren
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