[MODERATED] Re: [PATCH v3 3/6] PERFv3

On Thu, Feb 07, 2019 at 03:41:05PM -0800, speck for Andi Kleen wrote:
> From: Andi Kleen <[email protected]>
> Subject:  x86/pmu/intel: Add perf event attribute to control RTM
> 
> Add a "force_rtm_abort" attribute per perf event attribute
> to allow user programs to opt in to use counter 3 and disable
> TSX while the perf event is active.
> 
> Also add a "allow_rtm" attribute to allow programs to
> make sure TSX is enabled during the measurement (e.g.
> if they want to measure TSX itself)
> 
> This allows non root programs to override the defaults
> for their needs.
> 
> This is also needed for correct semantics in guests,
> so that the KVM PMU can set the correct default
> for its guests.
> 
> We use config2 bits 0/1 in the core PMU for these
> interfaces.

Again; why? This isn't needed _at_all_.