Ignore hyper threading cores

[sagudev]

Hyper thread cores shows in systems as two cores, but for some workload (and I suspect servo is one of them) using both cores for parallelism can actually hurt performance. Does this tool handle this, or does it really just assign jobs to any cores? By looking at:

perf-analysis-tools/studies/example/study.toml

Line 16 in 52729d6

2cpu = [14, 15]

I suspect it might be the later.

[delan]

thanks! yes, we effectively disable hyperthreading in isolate-cpu-for-shell.sh :)

for example, if your machine has 16 cores and 32 threads, paired like (0, 16) … (15, 31), then in the 2cpu configuration we would dedicate cpu 14 and cpu 15 to the workload, offline cpu 30 and cpu 31, and leave all others running normally.