Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during per-process profiling of STREAM benchmark on Intel Xeon Phi

[Andi Kleen]

> I was trying to get a feel for how that compares to what we can do
> today. For other reasons (e.g. fd exhaustion), opening NR_CPUS * n

You just have to increase the fd limit. The 1024 fd default is just
archaic for larger systems and doesn't really make any sense because
it only controls very small amounts of kernel memory.

> events might not be a great idea on systems with a huge number of CPUs.
> We might want a heuristic in the perf tool regardless.

But there's no alternative: we have to measure all CPUs with all events.

-andi