Jeff Pollard <[email protected]> wrote: jp> Overnight we do some data collection that is stored in Riak, and jp> just last night we had one of our server's load spike very high and jp> just drop back down to more acceptable levels. You can see a graph jp> of it [1]here.
Jeff, all that load average tells you is a weighted average of how many processes are runnable: running or ready to run but no CPU is available. Linux also seems to include processes in disk wait state, see http://en.wikipedia.org/wiki/Load_(computing). I don't have any specific knowledge of a Linux kernel's treatment of pthreads in computing the load average, but it wouldn't surprise me each thread in disk wait were included. Riak will start a pool of Pthreads for I/O work, see the +A flag in /etc/riak/vm.args (default Linux path), e.g. ## Enable kernel poll and a few async threads +K true +A 64 If you're interested in better measurements, "iostat -x" will give you much more useful information about CPU & disk usage than load average will. Intervals of 5 seconds are about the largest worth watching; anything larger loses too much in the average. 1 second is ideal, IMHO. -Scott _______________________________________________ riak-users mailing list [email protected] http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
