Re: [PATCH 1/3] x86, perf: Use a new PMU ack sequence

2015-10-22 Thread Ingo Molnar
* Andi Kleen wrote: > > > v2: > > > Use new ack sequence unconditionally. Remove pmu reset code. > > > > So this is not something we can easily revert if things go bad. Esp. > > since you build on it with the next patches. > > Ok, and? Sigh, you are being disruptive again. > You want me to

Re: [PATCH 1/3] x86, perf: Use a new PMU ack sequence

2015-10-22 Thread Ingo Molnar
* Andi Kleen wrote: > > > v2: > > > Use new ack sequence unconditionally. Remove pmu reset code. > > > > So this is not something we can easily revert if things go bad. Esp. > > since you build on it with the next patches. > > Ok, and? Sigh, you are being disruptive

Re: [PATCH 1/3] x86, perf: Use a new PMU ack sequence

2015-10-21 Thread Andi Kleen
> > v2: > > Use new ack sequence unconditionally. Remove pmu reset code. > > So this is not something we can easily revert if things go bad. Esp. > since you build on it with the next patches. Ok, and? You want me to go back to the previous patch? That one is easily undoable (just disable the

Re: [PATCH 1/3] x86, perf: Use a new PMU ack sequence

2015-10-21 Thread Peter Zijlstra
On Wed, Oct 21, 2015 at 01:16:06PM -0700, Andi Kleen wrote: > From: Andi Kleen > > The SKL PMU code had a problem with LBR freezing. When a counter > overflows already in the PMI handler, the LBR would be frozen > early and not be unfrozen until the next PMI. This means we would > get stale LBR

[PATCH 1/3] x86, perf: Use a new PMU ack sequence

2015-10-21 Thread Andi Kleen
From: Andi Kleen The SKL PMU code had a problem with LBR freezing. When a counter overflows already in the PMI handler, the LBR would be frozen early and not be unfrozen until the next PMI. This means we would get stale LBR information. Depending on the workload this could happen for a few

[PATCH 1/3] x86, perf: Use a new PMU ack sequence

2015-10-21 Thread Andi Kleen
From: Andi Kleen The SKL PMU code had a problem with LBR freezing. When a counter overflows already in the PMI handler, the LBR would be frozen early and not be unfrozen until the next PMI. This means we would get stale LBR information. Depending on the workload this could

Re: [PATCH 1/3] x86, perf: Use a new PMU ack sequence

2015-10-21 Thread Peter Zijlstra
On Wed, Oct 21, 2015 at 01:16:06PM -0700, Andi Kleen wrote: > From: Andi Kleen > > The SKL PMU code had a problem with LBR freezing. When a counter > overflows already in the PMI handler, the LBR would be frozen > early and not be unfrozen until the next PMI. This means we

Re: [PATCH 1/3] x86, perf: Use a new PMU ack sequence

2015-10-21 Thread Andi Kleen
> > v2: > > Use new ack sequence unconditionally. Remove pmu reset code. > > So this is not something we can easily revert if things go bad. Esp. > since you build on it with the next patches. Ok, and? You want me to go back to the previous patch? That one is easily undoable (just disable the