Very simple tool to measure memory latency, especially in NUMA environment.

(see README.ja.md in Japanese)

• C++11 (C++0x on GCC 4.4.7 is also supported)
• libnuma

Just make!

numa_memory_latency [bufsize] [nloop]
numa_memory_latency -h

bufsize is the buffer size (in KiB) that walk memory access. This must be less than the size of memory that you want to measure and should be much greater than the size of the one lower level memory; for example, if you want to measure latency of L3 cache, bufsize must be less than the size of L3 cache and should be much greater than the size of L2 cache.

nloop is the number of walk loop. You should specify enough large number to get accurate result.

On Dual Xeon E5 2630L v2 system, which have

• 32KiB L1 data cache /core
• 256KiB L2 cache /core
• 15MiB L3 cache /socket

you can:

• numa_memory_latency 16 8192 to measure L1 data cache latency.
• numa_memory_latency 200 2048 to measure L2 cache latency.
• numa_memory_latency 1200 1024 to measure L3 cache latency.
• numa_memory_latency 256000 256 to measure main memory latency (on both local and remote node).

GNU GPL v2

UMEZAWA Takeshi