----- Original Message -----
From: Darren Reed <darren.r...@sun.com>
Date: Thursday, June 25, 2009 6:35 pm
Subject: Re: [crossbow-discuss] inception review summary of PSARC/2009/364 -
dlstat and flowstat
To: Shrikrishna Khare <Shrikrishna.Khare at Sun.COM>
Cc: James Carlson <carlsonj at workingcode.com>, gdamore at opensolaris.org,
crossbow-discuss at opensolaris.org
> Shrikrishna Khare wrote:
> >
> >Here is an alternative (from the discussion Nicolas and I had a while
> ago).
> >
> >1. dlstat -k -p > snap1.txt # Dump all the statistics
> in parsable format, output redirected to snap1.txt. This option is
> part of the originally proposed man page.
> >2. dlstat -r -h # Display receive side per
> hardware lane statistics.
> >3. dlstat -r -h -d snap1.txt # Diff "current receive
> side per hardware lane stats" with the stats saved in snap1.txt and display.
> >4. dlstat -k -p > snap2.txt # Dump all the statistics
> in parsable format, output redirected to snap2.txt.
> >5. dlstat -t -h -d snap1.txt -D snap2.txt # Diff "transmit side per
> hardware lane stats" saved in snap2.txt with the stats saved in
> snap1.txt and display.
> >
> >This approach not only avoids resetting statistics but also provides
> an easy to use interface for diff calculation.
>
> Why are you building "diff" capability into dlstat?
> Why aren't the various incarnations of diff suitable for use here?
> Isn't it better to provide output that is friendly to diff(1) use?
> My assertion is that if the output is friendly to diff(1), then you don't
> need to build in diff capability and that the output will also then be
> friendly to many other commands.
- I did not find diff(1) option that can compute arithmetic difference.
- Moreover, even if there is some diff variant that can do it, consider the use
case as in example above:
Diff "current receive side per hardware lane stats" with the stats saved in
snap1.txt and display.
It is still cumbersome to do an additional
dlstat -k -p > snap3.txt
<arithmatic diff> snap1.txt snap3.txt
and then hunt through the machine parsable format to look for specific
fields of your interest - per hardware lane stats in our example.
Having a complete snapshot at particular instant (dlstat -k -p <file> and
then having ability to request diff against statistics of our interest (e.g.
dlstat -r -h -d <file>) looks appealing to me in comparison.
Moreover, you can then do fancier stuff like:
dlstat -r -h -d <file> -i 2
which will report diffs with the file after every 2 seconds.
Essentially, the proposed approach is aimed at catering to all 'reset' stats
requirement, without really resetting anything.
>
> Darren
>
