Messages in this thread |  | | Date | Tue, 21 Oct 2014 00:06:54 -0400 (EDT) | From | Vince Weaver <> | Subject | Re: [RFC 0/5] CR4 handling improvements |
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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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