Thursday Jan 24, 2013

dtrace profiling


DTrace never fails to impress me in it's ability to simply find the answer to a technical question. My only problem is remembering the syntax, so I though I'd blog it here.

I could see from mpstat my CPU it was all being consumed in userland, so this simple dtrace command helped identify the culperit.

# dtrace -n 'profile-1001 /arg1/{@[execname, ustack()]=count()}END{trunc(@,10)}'

Showed me the top 10 stacks found, aggregated by process name too. It showed me in my case that pkgrecv was taking the CPU and it was infact the libcurl part..

Useful information for me



Monday Oct 17, 2011

Useful measurement

One of the talks I went to at Oracle Open World was one on measuring performance of your application on an Oracle database. The talk was by Cary Millsap of Method R titled  "Instrumentation: Why You Should Care"

It was interesting in many ways, topics such as writing debug data to a ring bugger of shared memory reminded me of how we used to work before dtrace came a long.

There was  one fantastic quote from Mr Millsap, which I think is worth repeating

 "If obviously different experiences yield the same measurement, then clearly you're measuring the wrong thing"

 Sage words indeed


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Chris W Beal

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