Stats Output, Counters vs. Gauge.
time at digg.com
Tue Jan 24 09:39:13 UTC 2006
I'm trying to graph the output of memcache::getExtendedStats() in
RRDtool (Cacti, actually), but can't quite figure out which stats are
counters (always increasing) vs. gauges (a measure of the current value,
may rise or fall).
I had assumed that curr_items, total_connections, and total_items would
be gauges, but it looks like at least curr_items is a counter, or items
aren't flushed from the cache (I put things in the cache with an expiry
of 30 seconds in all cases).
Here's a screenshot:
Notice that the Current Items statistic is increasing about linearly
(the graph is logarithmic, so it looks like it's levelling off, but it
isn't). The two places where the graph drops is where I restarted
memcached. I do not expect this. Does anyone have a definitive list of
which items are counters and which are gauges?
Once I get the stats correct, I'll put the Cacti host template online
for people to graph their MemcacheD statistics, alongside the MySQL
Cacti host template here:
More information about the memcached