Performance monitoring?

[pll at lanminds.com]

In a message dated: Mon, 23 Dec 2002 11:32:12 EST
mike ledoux said:

>Is this different somehow from the %util field in 'iostat -x'?

The %util field will probably suffice, however, it appears to require 
a kernel patch for it to work (note, RH stock kernels already have 
the patch applied) and I can't seem to find the actual patch (after 
only 30 seconds of looking in /pub/linux/sct/fs/profiling/ where the 
'sysstat' web site states it should be).  I'll find the patch and 
play with it.  It might suffice for the people who care/are pestering me :)

>> The interesting thing is that iostat will tell you how many requests 
>> per second were made, and how much data per second was transferred, 
>> but there is no correlation between the two; i.e. I know how many 
>> requests were made, but not the size of those requests.
>
>'iostat -x' gives you an average request size.  You don't actually want
>to know the exact size of each individual request, do you?

Well, no, average size might suffice. 

>> Therefore, I have no idea what percentage of requests is represented
>> by the amount of data transferred.
>
>100%.

100% of the requests made, or 100% of the requests serviced?  Of the 
number of requests made per second, how many were actually completed?

Obviously the amount of data transferred == number of requests per 
second completed.  However, there may have been more requests made, 
than were completed.  How do you measure that delta?
-- 

Seeya,
Paul
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