Some queries

[Prachetaa]

I have some queries. I need to see the memory access pattern of a
particular program , i.e. to see the non-local memory accesses. I want
to see remote accesses through some counters if possible. Furthermore,
likwid-perfctr takes a program as an arguement, is there any way i can
measure the counters before and after the execution of the program? I
would also like to output the number of events that occured during the
execution of the application. Is it possible? Thank you very much for
your time and help.

[moebiusband]

Hello Prachetaa ,

there is a ready to use performance group for this it is called MEM.

If you use (on Nehalem or Westmere):

likwid-perfctr -C S0:0@S1:0 -g MEM sleep 5

will measure what traffic is there in the next 5 seconds.

Try:

likwid-perfctr -H -g MEM

to get documentation about the group.

There are several ways to use perfctr:

1. End to end measurements. You measure what happens in you total
application. The runtime related derived metrics are of course
averages then over the toal runtime:

likwid-perfctr -C N:0-3 -g MEM ./myApp

2. Profiling on node. You measure what is currently happening on an
node. See first example with sleep how to use this.

3. Timeline mode. You do a timeprofile for a group.

likwid-perfctr -c 0-3 -g MEM -d 500ms

Note that the MEM group is per socket. There is no way to get this
counters on a per core basis.
Please have a look in the WIKI. All features are well documented
there. Inform me if there a things not understandable in the
documentation:

http://code.google.com/p/likwid/wiki/LikwidPerfCtr

Greetings,

Jan