Hello All, Here is a patch against the central repo that adds sFlow monitoring. Please comment! http://www.inmon.com/technology/sfmc_20100923.zip
For background on this, please read: http://blog.sflow.com/2010/08/sflow-host-structures.html If you compile with this patch, then you can run with "memcached -u nobody -o sflow=on", and it will pick up configuration from /etc/ hsflowd.auto, such as: sampling=400 polling=20 agentIP=10.0.0.112 collector=10.0.0.111 6343 "agentIP" should be the IP of the server, and "collector" should be the IP of an sflow collector such as "sflowtool": http://www.inmon.com/bin/sflowtool-3.17.tar.gz (This config file is generated automatically if you install hsflowd, the host sFlow daemon from host-sflow.sourceforge.net which contributes an sFlow feed of server performance stats) Neil NOTES: (1). Provided the sampling-rate is set appropriately, the overhead should be roughly equivalent to adding one extra stats counter. The critical path is just a decrement-and-test on a per-thread counter (no locking). (2). The changes are all within "#ifdef SFLOW" except for (3) below. (3). I changed memcached.h:struct conn->request_addr to be of type struct sockaddr_storage so it would work for IPv6 too.
