On Tue, 2007-11-13 at 13:04 -0800, Evan Rempel wrote:
We were running syslog-ng with default setting for time_sleep (which is 0) and were consuming approx 50% of a single CPU with syslog-ng. We were concerned about scalability because syslog-ng is single threaded, so we started tuning with time_sleep. We set it to 5 and adjusted related parameters (log_fetch_limit(250), log_fifo_size(1000000)) and now we are seeing a sawtooth CPU usage with a small IO wait (2%) constant on top of the "user" cpu sawtooth.
Tooth cpu duration
1 1-10% 25 minutes 2 2-10% 10 minutes 3 3-10% 10 minutes 4 4-10% 10 minutes
This pattern repeats.
Any ideas on why the sawtooth pattern started appearing only after we adjusted these settings?
Could you post an mrtg image? I guess you were gathering this input from an image of some kind, and it's very difficult to understand without actually seeing the picture. You know a picture is worth thousand words :) which applies to this case very nicely. You can send it to me in private, if you think it contains sensitive information. -- Bazsi