Re: [RFC 0/5] CR4 handling improvements

[Vince Weaver]

On Tue, 14 Oct 2014, Andy Lutomirski wrote:

> This little series tightens up rdpmc permissions.  With it applied,
> rdpmc can only be used if a perf_event is actually mmapped.  For now,
> this is only really useful for seccomp.

So just to be difficult...

I am aware of at least one group who is doing low-latency performance
measures using rdpmc on Linux.

They start the counters manually by poking the MSRs directly (bypassing 
perf_event_open()).

They use rdpmc, grateful for the fact that currently CR4 is set up so they 
can do this w/o patching the kernel.

These patches of course would break this use case...

Vince
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