[6001] in linux-scsi channel archive
Re: data transmission rate
daemon@ATHENA.MIT.EDU (H.Oura FCT Headquarters??)
Mon Mar 1 01:58:56 1999
To: Doug Ledford <dledford@redhat.com>
Cc: "H.Oura FCT Headquarters??" <oura@landmark.fct.cs.fujitsu.co.jp>,
linux-scsi@vger.rutgers.edu
In-reply-to: Your message of Sat, 27 Feb 1999 09:10:24 EST.
<36D7FCD0.7283EE91@redhat.com>
Date: Mon, 01 Mar 1999 15:57:09 +0900
From: "H.Oura FCT Headquarters??" <oura@landmark.fct.cs.fujitsu.co.jp>
In message <36D7FCD0.7283EE91@redhat.com>you write:
>"H.Oura FCT Headquarters??" wrote:
>>
>> Hi,
>> I've calculated data transmission rate of my SCSI-2 disk.
>
>No, you haven't. You've calculated the combined transfer period of
>128KB + the overhead and latency of a single command creation,
>initiation, response, and teardown.
[snip]
Sorry, that's right.
It's not data transmission rate of SCSI-2 disk.
[snip]
> A quick start though might be to issue a
>series of TEST_UNIT_READY commands to isolate the command startup,
>initiation, completion, and teardown latencies. Get a msec measurement
>on that command, then subtract it from 24msecs and that will give you
>how much time was spent sending the 128K to the drive.
I've got a msec of TEST_UNIT_READY. It was 8msec.
So, 128KB data sending time = 24msec - 8msec = 16msec.
reculculated data transfer rate = 8.2MB/sec.
(That's much better than the 1st one)
Thanks to Doug and lance for advice.
Hironobu Oura
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