Date: Sun, 02 Jan 2000 14:26:13 -0800 From: R Joseph Wright <rjoseph@nwlink.com> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: some performance issues Message-ID: <386FD085.93BFA305@nwlink.com> References: <386C0676.F39EC477@3-cities.com> <386C2354.ABD1ED54@nwlink.com> <386C3173.1D695393@3-cities.com> <386C543D.6E59C9DF@nwlink.com> <19991231104441.C2609@emu.sourcee.com> <386CE8AB.29A140B5@nwlink.com> <386CF9DC.B71A9887@3-cities.com> <386D3D3C.C92D02A3@nwlink.com> <386D5C88.B8257D45@3-cities.com> <386D8ABD.C2894A91@nwlink.com> <20000101160159.O1528@freebie.lemis.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Greg Lehey wrote:
> iozone is not really a storage device testing program. Use rawio (in
> the Ports Collection) for that: it bypasses the cache. Read carefully
> the warnings which tell you that you should not use the write tests on
> a file system which contains data you want to keep.
>
> > Kent, I tried that, only for me it worked doing "iozone 160". Here is
> > my results:
> >
> > 11483869 bytes/second for reading
> > 15155142 bytes/second for writing
>
> This is sequential access. You'll never get that in practice.
>
> > Is that really slow? It's nowhere near 33MB/second.
>
> 33 MB/s is the transfer rate from disk buffer to CPU. The transfer
> rate off the platter is slower, and your speeds there look pretty
> good. But remember that they're the ideal case.
>
> > I have a Maxtor 7000rpm with UDMA66 capabilities, although I'll have
> > to wait for -STABLE to support that, and a new motherboard as well.
> > I may recompile with the old flags just to see the difference.
>
> I'd be interested to see the difference, but I don't think it'll be
> very much. Try both with rawio, and look at the random access
> results, which are the only ones that count in practice.
>
> Greg
I tried rawio, and got the following using flags 0xb0ffb0ff:
Random Read Random Write
ID K/sec /sec K/sec /sec
anon 25352.3 1560 16548.4 1024
With flags set at 0x80ff80ff, I got:
K/sec /sec
12992.0 806
After that, it core dumped. But I got double the speed with the new
flags! I was pretty amazed. I did the test on an empty partition, so as
not to disturb anything.
BTW, your book The Complete FreeBSD has been tremendously helpful! Thank
you 8)
Joseph
> --
> When replying to this message, please copy the original recipients.
> For more information, see http://www.lemis.com/questions.html
> Finger grog@lemis.com for PGP public key
> See complete headers for address and phone numbers
>
> To Unsubscribe: send mail to majordomo@FreeBSD.org
> with "unsubscribe freebsd-questions" in the body of the message
--
Best Regards, Joseph
You will do foolish things,
but do them with enthusiasm. Colette.
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?386FD085.93BFA305>