We're using Newrelic to measure our Python/Django application performance. Newrelic is reporting that across our system "Memcached" is taking an average of 12ms to respond to commands.

Drilling down into the top dozen or so web views (by # of requests) I can see that some Memcache get take up to 30ms; I can't find a single use of Memcache get that returns in less than 10ms.

More details on the system architecture:

• Currently we have four application servers each of which has a memcached member. All four memcached members participate in a memcache cluster.
• We're running on a cloud hosting provider and all traffic is running across the "internal" network (via "internal" IPs)
• When I ping from one application server to another the responses are in ~0.5ms

Isn't 10ms a slow response time for Memcached?

As far as I understand if you think "Memcache is too slow" then "you're doing it wrong". So am I doing it wrong?

Here's the output of the memcache-top command:

memcache-top v0.7   (default port: 11211, color: on, refresh: 3 seconds)

INSTANCE        USAGE   HIT %   CONN    TIME    EVICT/s GETS/s  SETS/s  READ/s  WRITE/s 
cache1:11211    37.1%   62.7%   10      5.3ms   0.0     73      9       3958    84.6K   
cache2:11211    42.4%   60.8%   11      4.4ms   0.0     46      12      3848    62.2K   
cache3:11211    37.5%   66.5%   12      4.2ms   0.0     75      17      6056    170.4K  

AVERAGE:        39.0%   63.3%   11      4.6ms   0.0     64      13      4620    105.7K  

TOTAL:      0.1GB/  0.4GB       33      13.9ms  0.0     193     38      13.5K   317.2K  
(ctrl-c to quit.)

** Here is the output of the top command on one machine: ** (Roughly the same on all cluster machines. As you can see there is very low CPU utilization, because these machines only run memcache.)

top - 21:48:56 up 1 day,  4:56,  1 user,  load average: 0.01, 0.06, 0.05
Tasks:  70 total,   1 running,  69 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.0%us,  0.0%sy,  0.0%ni, 99.7%id,  0.0%wa,  0.0%hi,  0.0%si,  0.3%st
Mem:    501392k total,   424940k used,    76452k free,    66416k buffers
Swap:   499996k total,    13064k used,   486932k free,   181168k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                                               
 6519 nobody    20   0  384m  74m  880 S  1.0 15.3  18:22.97 memcached                                                                                              
    3 root      20   0     0    0    0 S  0.3  0.0   0:38.03 ksoftirqd/0                                                                                            
    1 root      20   0 24332 1552  776 S  0.0  0.3   0:00.56 init                                                                                                   
    2 root      20   0     0    0    0 S  0.0  0.0   0:00.00 kthreadd                                                                                               
    4 root      20   0     0    0    0 S  0.0  0.0   0:00.00 kworker/0:0                                                                                            
    5 root      20   0     0    0    0 S  0.0  0.0   0:00.02 kworker/u:0                                                                                            
    6 root      RT   0     0    0    0 S  0.0  0.0   0:00.00 migration/0                                                                                            
    7 root      RT   0     0    0    0 S  0.0  0.0   0:00.62 watchdog/0                                                                                             
    8 root       0 -20     0    0    0 S  0.0  0.0   0:00.00 cpuset                                                                                                 
    9 root       0 -20     0    0    0 S  0.0  0.0   0:00.00 khelper                                                                                                
...output truncated...