Plugin – imudp
This plugin maintains statistics for each listener and for each worker thread.
The listener statistic is named starting with “imudp”, followed followed by the listener IP, a colon and port in parenthesis. For example, the counter for a listener on port 514 (on all IPs) with no set name is called “imudp(*:514)”.
If an “inputname” is defined for a listener, that inputname is used instead of “imudp” as statistic name. For example, if the inputname is set to “myudpinut”, that corresponding statistic name in above case would be “myudpinput(*:514)”. This has been introduced in 7.5.3.
The following properties are maintained for each listener:
- submitted – total number of messages submitted for processing since startup
The worker thread (in short: worker) statistic is named “imudp(wX)” where “X” is the worker thread ID, which is an monotonically increasing integer starting at 0. This means the first worker will have the name “imudp(w0”), the second “imudp(w1)” and so on. Note that workers are all equal. It doesn’t really matter which worker processes which messages, so the actual worker ID is not of much concern. More interesting is to check how the load is spread between the worker. Also note that there is no fixed worker-to-listener relationship: all workers process messages from all listeners.
Note: worker thread statistics are available starting with rsyslog 7.5.5.
The following properties are maintained for each worker thread:
- called.recvmmsg – number of recvmmsg() OS calls done
- called.recvmsg – number of recvmsg() OS calls done
- msgs.received – number of actual messages received
Note: usually either one of “called.recvmmsg” or “called.recvmsg” is non-zero. This is because these are alternative kernel interfaces and the one to be used is selected based on kernel capabilities. However, there are two counters, as the system call type used has important performance implications, and so we thought this information needs to be exposed.
On systems supporting recvmmsg, the quotient msgs.received / caled.recvmmsg tells the average number of messages that could be pulled from the kernel buffers with a single syscall.