Statistics
How to determine if varnish and the FPC of your page achieve optimally.
To use the commands in this article we assume you have configured aliases as described in Varnish Basics
Cache hit rate
The cache hit rate is the percentage of requests served by varnish and not your PHP server. The higher this percentage the higher the speed your visitors are serviced with.
Find this percentage by using this command:
$ varnishstat
Uptime mgt: 0+19:09:45 Hitrate n: 10 100 236
Uptime child: 0+19:09:46 avg(n): 0.1918 0.2552 0.2491
NAME CURRENT CHANGE AVERAGE AVG_10 AVG_100 AVG_1000
MGT.uptime 0+19:09:45
MAIN.uptime 0+19:09:46
MAIN.sess_conn 4175060 141.71 60.52 60.62 57.82 57.82
MAIN.client_req 4245300 141.71 61.54 60.62 57.82 57.82
MAIN.cache_hit 938985 42.91 13.61 10.90 9.17 9.17
MAIN.cache_miss 2457485 98.80 35.62 49.11 48.09 48.09
...
...
...The Hitrate percentage represents the past n requests. In this example: Last 10 requests: 19,18% last 100 requests: 25,52% Last 236 requests: 24,91%
Whether these percentages are low or high depends mainly on the application itself. A shop for example which has a very high conversion will have a lower percentage. Because of the fact that relatively more people are in the checkout which is not being cached.
Monitor cache misses
To find out what pages are resulting in cache misses you can use this command:
$ varnishncsa -F '%U%q %{Varnish:hitmiss}x' | grep missMemory usage
To check if varnish uses just enough or too much memory, use the varnishstat command:
We are now looking for the g_bytes en g_space stats.
$ varnishstat
NAME CURRENT CHANGE AVERAGE AVG_10 AVG_100 AVG_1000
MGT.uptime 0+19:09:45
MAIN.uptime 0+19:09:46
...
...
SMA.s0.c_bytes 43.68G 881.87K 657.40K 781.48K 795.49K 793.00K
SMA.s0.c_freed 39.68G 900.86K 597.19K 784.63K 795.83K 793.07K
SMA.s0.g_alloc 1000036 74.79 . 999787.76 998530.86 997099.17
SMA.s0.g_bytes 4.00G -18.99K . 4.00G 4.00G 4.00G
SMA.s0.g_space 110.82K 18.99K . 82.45K 76.96K 62.70Kg_bytesTotal memory in useg_spaceAvailable varnish memory