Subject: Re: Disk performance under NetBSD on A3000
To: None <bsieker@TechFak.Uni-Bielefeld.DE>
From: Andreas Johansson <email@example.com>
Date: 04/25/1995 01:24:48
According to bsieker@TechFak.Uni-Bielefeld.DE:
> > I'm seeing poor disk performance under NetBSD-current on my A3000.
> > Under ADOS, I see about 1.7-2.0 megabytes per second (via sysinfo)
> > while under NetBSD, I see about 500 kilobytes per second
> > (dd if=/dev/zero of=zzzzz bs=1024k count=10).
> Use a higher blocksize like 64k, and you'll see much better
64k is bigger than 1024k?
> performance. It should be about the same value as you get with
> And transfer more blocks, too; most accurate results are
> obtained if you transfer several ten MB. (more than RAM preferably, or
> the Cache may obscure the true disk performance.)
Well, he is actually transferring 10Mb:s, this is reliable enough when we
are talking about 500kB/s vs. 2MB/s.
Also, if you are afraid the cache will obscure the values, it would be
enough to exceed the cache size, no? The cache is much smaller than the
amount of ram, on my system <1Mb with 16Mb ram.
You are probably talking about reads from the raw device, he is talking
about writes to the filesystem.
> > What disk performance numbers are others seeing?
> I get 2.7 MB/s with IBM 0662S Rev. 3 30, (synchronous) on an A3000 w/
> A3640 under NetBSD
Probably not with the above command going through the filesystem instead
of the raw device.
On my A4000/040 with A4091 scsi-II fast controller and a MicroPolis 4110
(1Gb Fast SCSI-II disk), I get ~550kB/s. Reading the same file isn't much
better, 650k/s. I suspect the stupid 3640 interface is to blame here
Now, raw speed, that's another thing. Under NetBSD I get 3MB/s (64kB blocks)
and under ados 4.5MB/s (1MB blocks).
> I get about 2.0 MB/s with SysInfo and SCSIspeed (asynchronous) under
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