Metrics (Intel) - phoronix/c-ray
This is a test of C-Ray, a simple raytracer designed to test the floating-point CPU performance. This test is multi-threaded (16 threads per core), will shoot 8 rays per pixel for anti-aliasing, and will generate a 1600 x 1200 image.
c-ray - pid 12476 On_CPU 0.988 On_Core 7.901 IPC 1.438 Retire 0.740 (74.0%) FrontEnd 0.104 (10.4%) Spec 0.008 (0.8%) Backend 0.148 (14.8%) Elapsed 26.61 Procs 130 Minflt 2514 Majflt 0 Utime 210.25 (100.0%) Stime 0.00 (0.0%) Start 442452.65 Finish 442479.26
This benchmark runs for slightly less than 30 seconds. During that time it is scheduled on all cores of the CPU almost 100% of the time.
Topdown metrics show it isn’t slowed much by issues in front end, backend or bad speculation.Metrics (AMD) - phoronix/c-ray
sh - pid 5058 On_CPU 0.977 On_Core 15.625 IPC 1.844 FrontCyc 0.001 (0.1%) BackCyc 0.079 (7.9%) Elapsed 11.36 Procs 258 Minflt 2925 Majflt 0 Utime 177.50 (100.0%) Stime 0.00 (0.0%) Start 40959.30 Finish 40970.66
Process Tree - phoronix/c-ray
A total of 130 processes are run as part of the application, it is otherwise symmetric across these processes.
About this graph
CPU utilization shows almost even usage across all cores.
The IPC is a little over 1.4
About this graph
The plot shows across three runs of the benchmark.
Overall, this benchmark is spending most all time scheduled on the cores and most of that time retiring instructions. No major bottlenecks stick out for further investigation, but instead this is a useful cross reference point with other workloads or other platforms.
Next step (done): Investigate why wspy runs on Ryzen occasionally miss exit events e.g. ~1 of the 256 threads launched. Investigated this and appears that the events might still occur but information such as the child pid might not always be available in a ptrace(PTRACE_GETEVENTMSG) call. I’ve made the ptrace2 engine more robust for this possibility.