PlayingWithCache

sample applications to see effect of CPU cache

To compile the applications: bash compile.sh

Example how to run datalocality:

Not exploiting locality

$ time ./datalocality

real 0m1.866s user 0m1.850s sys 0m0.019s

Exploiting locality

$ time ./datalocality 1

real 0m0.088s user 0m0.066s sys 0m0.022s

$ time ./cachecoherency 1000000000 0 100 0 8 Level 1 Data cache line size=64 rd_offset=0 wr_offset=100 num_iter=1000000000 writeThread started on cpu=8 ret_affinity=0 readThread started on cpu=0 ret_affinity=0 finished wr_data=1000000000 rd_data=1000000000

real 0m3.512s user 0m6.930s sys 0m0.038s

Example how to run cachecoherency:

Examples executed on a CPU with the following charateristics

2 CPU sockets (2 numa nodes) with each 8 cpu cores each. Each core has 2 hyperthreads

Each thread runs on different NUMA node + data offset between read & write > L1 cache size

$ time ./cachecoherency 1000000000 0 100 0 8 Level 1 Data cache line size=64 rd_offset=0 wr_offset=100 num_iter=1000000000 writeThread started on cpu=8 ret_affinity=0 readThread started on cpu=0 ret_affinity=0 finished wr_data=1000000000 rd_data=1000000000

real 0m3.512s user 0m6.930s sys 0m0.038s

Each thread runs on different NUMA node + data offset between read & write < L1 cache size

$ time ./cachecoherency 1000000000 0 1 0 8 Level 1 Data cache line size=64 rd_offset=0 wr_offset=1 num_iter=1000000000 readThread started on cpu=0 ret_affinity=0 writeThread started on cpu=8 ret_affinity=0 finished wr_data=1000000000 rd_data=1000000000

real 0m9.686s user 0m17.690s sys 0m0.048s

Each thread runs on same NUMA node + data offset between read & write < L1 cache size

$ time ./cachecoherency 1000000000 0 1 0 5 Level 1 Data cache line size=64 rd_offset=0 wr_offset=1 num_iter=1000000000 readThread started on cpu=0 ret_affinity=0 writeThread started on cpu=5 ret_affinity=0 finished wr_data=1000000000 rd_data=1000000000

real 0m8.952s user 0m15.920s sys 0m0.056s

Each thread runs on same hyperthread + data offset between read & write < L1 cache size

$ time ./cachecoherency 1000000000 0 1 0 0 Level 1 Data cache line size=64 rd_offset=0 wr_offset=1 num_iter=1000000000 readThread started on cpu=0 ret_affinity=0 writeThread started on cpu=0 ret_affinity=0 finished wr_data=1000000000 rd_data=1000000000

real 0m6.821s user 0m6.824s sys 0m0.003s

Each thread runs on different hyperthread of same cpu core+ data offset between read & write < L1 cache size

$ time ./cachecoherency 1000000000 0 1 0 16 Level 1 Data cache line size=64 rd_offset=0 wr_offset=1 num_iter=1000000000 writeThread started on cpu=16 ret_affinity=0 readThread started on cpu=0 ret_affinity=0 finished wr_data=1000000000 rd_data=1000000000

real 0m7.055s user 0m11.320s sys 0m0.032s