Skip site navigation (1)Skip section navigation (2)
Date:      Fri, 29 Nov 1996 23:44:08 -0500 (EST)
From:      "John S. Dyson" <toor@dyson.iquest.net>
To:        mango@staff.communique.net (Raul Zighelboim)
Cc:        hackers@freefall.freebsd.org, hardware@freefall.freebsd.org
Subject:   Re: Adaptec UW controller and Seagate Elite performance ?
Message-ID:  <199611300444.XAA09675@dyson.iquest.net>
In-Reply-To: <c=US%a=_%p=Communique._Inc.%l=KAORI-961130042812Z-340@kaori.communique.net> from "Raul Zighelboim" at Nov 29, 96 10:28:12 pm

next in thread | previous in thread | raw e-mail | index | archive | help
> 
> # bonnie -s 40  	(akira, http running)
>    -------Sequential Output-------- ---Sequential Input-- --Random--
>    -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
> MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
> 40  3271 34.8  3085 13.0  1559  8.3 10330 97.1 44763 95.7 991.0 20.4
> 
> and
> IOZONE performance measurements:
>         2039008 bytes/second for writing the file
>         34861747 bytes/second for reading the file
> 
> It bothered me that:
> 1- reading is 20 times faster than writing

You are seeing the results of caching.  The system remembers what
is written so that it doesn't have to unnecessarily re-read the
data.

>
> 2- 2Mbytes/s for writing seems slow, even if this was a scsi-2 and not
> an 
> scsi fast and wide drive.
> 
I don't know why your iozone write perf is so slow, unless you are writing
512 bytes at a time.  Note also, that you might not have the write
behind caching enabled on your drive.

Try the following commands:

# iozone auto
and
# iozone 40 8192
and
# iozone <size-of-memory*2> 8192

and let me know the results.


John
dyson@freebsd.org



Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199611300444.XAA09675>