Hi,
 
its me again thinking about measurement of response time. I have a new idea and just wanted to hear from you what you think about it.
I am running a dd with a bs of 8k/4k against a fileserver for a couple of minutes and during different daytimes.
 
While the dd is running i do capture the networkstream and create a statistic for NFSv3-ops
 
tetherreal -i eth0 -z rpc,100003,3
 
This gives me an overview of the RTT's during this run of dd.
What do you think about this method? I can use sio as well for generating random IO but the method will remain the same.
 
Best Regards and thanks in advance for any opinions on that
 
Jochen

From: Miller, James [mailto:James.Miller@netapp.com]
Sent: Friday, September 22, 2006 7:27 PM
To: Willeke, Jochen
Subject: Re: Response time measurement

Isn't it 8.72ms or .00872secs
... Jim Miller sent from blackberry

-----Original Message-----
From: Willeke, Jochen <Jochen.Willeke@wincor-nixdorf.com>
To: NetApp Toasters List <toasters@mathworks.com>
Sent: Fri Sep 22 08:13:05 2006
Subject: Response time measurement

Hi folks,

i am still thinking about some figures which help me considering
different fileservers. After doing some research i think one point is
the response time given by the system.

I did a lot of testing with sio and but the results i got are some kind
of strange.

A test with SIO e.g. brings following result:

./sio_ntap_linux 100 0 8k 100m 10 1 /mnt/test15
Version: 3.00

SIO_NTAP:
Inputs
Read %:         100
Random %:       0
Block Size:     8192
File Size:      104857600
Secs:           10
Threads:        1
File(s):        /mnt/test15
Outputs
IOPS:           114578
KB/s:           916626
IOs:            1145782
Terminating threads ...Killed

First there are the KB/S. Much to fast even for a 1Gbit network. And the
second is the response time. I calculated the following:

1s /  114578 (IOPS) = 0,00872 ms (response time)

This cannot be true at all :-)
Does SIO read the same block all the time (due to 0%random read), or do
i have any kind of mistake in my test?!?

Perhaps someone can help.

Best Regards and a nice weekend

Jochen