Re: [PATCH V3 1/4] perf: Add PERF_RECORD_SWITCH to indicate context switches

2015-07-08 Thread Arnaldo Carvalho de Melo
Em Wed, Jul 08, 2015 at 04:42:03PM +0300, Adrian Hunter escreveu: > On 08/07/15 16:28, Arnaldo Carvalho de Melo wrote: > > Em Wed, Jul 08, 2015 at 12:52:40AM +0200, Peter Zijlstra escreveu: > >> On Tue, Jul 07, 2015 at 01:13:59PM -0300, Arnaldo Carvalho de Melo wrote: > >>> Em Tue, Jul 07, 2015 at

Re: [PATCH V3 1/4] perf: Add PERF_RECORD_SWITCH to indicate context switches

2015-07-08 Thread Adrian Hunter
On 08/07/15 16:28, Arnaldo Carvalho de Melo wrote: > Em Wed, Jul 08, 2015 at 12:52:40AM +0200, Peter Zijlstra escreveu: >> On Tue, Jul 07, 2015 at 01:13:59PM -0300, Arnaldo Carvalho de Melo wrote: >>> Em Tue, Jul 07, 2015 at 05:36:14PM +0200, Peter Zijlstra escreveu: > To help userspace in plac

Re: [PATCH V3 1/4] perf: Add PERF_RECORD_SWITCH to indicate context switches

2015-07-08 Thread Arnaldo Carvalho de Melo
Em Wed, Jul 08, 2015 at 12:52:40AM +0200, Peter Zijlstra escreveu: > On Tue, Jul 07, 2015 at 01:13:59PM -0300, Arnaldo Carvalho de Melo wrote: > > Em Tue, Jul 07, 2015 at 05:36:14PM +0200, Peter Zijlstra escreveu: > > > > To help userspace in places where all it has is the union perf_event, we > >

Re: [PATCH V3 1/4] perf: Add PERF_RECORD_SWITCH to indicate context switches

2015-07-07 Thread Peter Zijlstra
On Tue, Jul 07, 2015 at 01:13:59PM -0300, Arnaldo Carvalho de Melo wrote: > Em Tue, Jul 07, 2015 at 05:36:14PM +0200, Peter Zijlstra escreveu: > > > To help userspace in places where all it has is the union perf_event, we > > > can reuse one bit in misc to state that, i.e. > > > > #define PERF_R

Re: [PATCH V3 1/4] perf: Add PERF_RECORD_SWITCH to indicate context switches

2015-07-07 Thread Arnaldo Carvalho de Melo
Em Tue, Jul 07, 2015 at 05:36:14PM +0200, Peter Zijlstra escreveu: > On Tue, Jul 07, 2015 at 10:44:37AM -0300, Arnaldo Carvalho de Melo wrote: > > Em Tue, Jul 07, 2015 at 10:25:52AM -0300, Arnaldo Carvalho de Melo escreveu: > > > Em Tue, Jul 07, 2015 at 11:36:39AM +0300, Adrian Hunter escreveu: > >

Re: [PATCH V3 1/4] perf: Add PERF_RECORD_SWITCH to indicate context switches

2015-07-07 Thread Peter Zijlstra
On Tue, Jul 07, 2015 at 10:44:37AM -0300, Arnaldo Carvalho de Melo wrote: > Em Tue, Jul 07, 2015 at 10:25:52AM -0300, Arnaldo Carvalho de Melo escreveu: > > Em Tue, Jul 07, 2015 at 11:36:39AM +0300, Adrian Hunter escreveu: > > > To make the event useful for privileged users also, if the > > > conte

Re: [PATCH V3 1/4] perf: Add PERF_RECORD_SWITCH to indicate context switches

2015-07-07 Thread Arnaldo Carvalho de Melo
Em Tue, Jul 07, 2015 at 10:25:52AM -0300, Arnaldo Carvalho de Melo escreveu: > Em Tue, Jul 07, 2015 at 11:36:39AM +0300, Adrian Hunter escreveu: > > To make the event useful for privileged users also, if the > > context is cpu-wide then the event will also provide the > > next or previous pid/tid.

Re: [PATCH V3 1/4] perf: Add PERF_RECORD_SWITCH to indicate context switches

2015-07-07 Thread Arnaldo Carvalho de Melo
Em Tue, Jul 07, 2015 at 11:36:39AM +0300, Adrian Hunter escreveu: > To make the event useful for privileged users also, if the > context is cpu-wide then the event will also provide the > next or previous pid/tid. > + /* > + * Records a context switch in or out (flagged by > + *

[PATCH V3 1/4] perf: Add PERF_RECORD_SWITCH to indicate context switches

2015-07-07 Thread Adrian Hunter
There are already two events for context switches, namely the tracepoint sched:sched_switch and the software event context_switches. Unfortunately neither are suitable for use by non-privileged users for the purpose of synchronizing hardware trace data (e.g. Intel PT) to the context switch. Tracep