Messages in this thread | | | Date | Sat, 4 Apr 2009 22:17:35 -0600 | Subject | Re: IO latency - a special case | From | "Trenton D. Adams" <> |
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On Sat, Apr 4, 2009 at 7:13 PM, Theodore Tso <tytso@mit.edu> wrote: > Trenton. Couple of things to try. First of all, it looks like your > application is multi-threaded. That's why it can drive up the load so > high, even though "ps" and "top" is only showing one process. Try > using the -f flag to strace so you can follow all of the processes and > threads fork()'ed or cloned()'ed from the initial process. > > In addition, here's a rather brute-force script that I've used when > trying to collect data when debugging performance or long-term > stability problems at customer sites. Very often it was used on > production machines where they don't allow random people to poke > around on it, so this was designed to be given to a sysadmin, who > would approve running it on their system, and some hours later, we > would get the tarball, and then try to figure out what the heck was > going on. > > It doesn't have to run out of cron, BTW; it also can be run from a > command-line, and some of the polling intervals adjusted smaller if > you need finer-grained resolution, or it can run as a stand-alone > daemon as well. > > - Ted
Hi Ted,
I would imagine it is multi threaded, though I am not positive. I am asking on IRC right now.
I will look into trying out your tests, and the -f flag. I will report back once I have more data. The good thing is that once the problem starts happening, it continues to happen. I think it happens until reboot, but I'm not positive. I'm about to try again, so we'll see, as I have not rebooted since last time.
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