Re: [RFC PATCH 5/7] perf, x86: use the PEBS auto reload mechanism when possible

2014-05-28 Thread Peter Zijlstra
On Wed, May 28, 2014 at 07:46:43AM -0700, Andi Kleen wrote: > On Wed, May 28, 2014 at 09:59:37AM +0200, Peter Zijlstra wrote: > > On Wed, May 28, 2014 at 02:18:08PM +0800, Yan, Zheng wrote: > > > When a fixed period is specified, this patch make perf use the PEBS > > > auto reload mechanism. This m

Re: [RFC PATCH 5/7] perf, x86: use the PEBS auto reload mechanism when possible

2014-05-28 Thread Andi Kleen
On Wed, May 28, 2014 at 09:59:37AM +0200, Peter Zijlstra wrote: > On Wed, May 28, 2014 at 02:18:08PM +0800, Yan, Zheng wrote: > > When a fixed period is specified, this patch make perf use the PEBS > > auto reload mechanism. This makes normal profiling faster, because > > it avoids one costly MSR w

Re: [RFC PATCH 5/7] perf, x86: use the PEBS auto reload mechanism when possible

2014-05-28 Thread Peter Zijlstra
On Wed, May 28, 2014 at 02:18:08PM +0800, Yan, Zheng wrote: > When a fixed period is specified, this patch make perf use the PEBS > auto reload mechanism. This makes normal profiling faster, because > it avoids one costly MSR write in the PMI handler. > You can't do this unconditionally. Like I t