Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-11-05 Thread Will Deacon
On Wed, Oct 30, 2013 at 09:56:15AM +, Peter Zijlstra wrote: > On Tue, Oct 29, 2013 at 11:36:52AM -0400, Vince Weaver wrote: > > It is true the current behavior is unexpected. What was the logic behind > > deferring to the next overflow for the update? Was it a code simplicity > > thing? Or

Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-31 Thread Vince Weaver
On Wed, 30 Oct 2013, Will Deacon wrote: > On Wed, Oct 30, 2013 at 02:13:11PM +, Vince Weaver wrote: > > Uncompiled too I guess? > > > > kernel/events/core.c: In function ‘perf_event_period’: > > kernel/events/core.c:3531: error: invalid type argument of ‘->’ (have > > ‘local64_t’) > > make[3]

Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-30 Thread Will Deacon
On Wed, Oct 30, 2013 at 02:13:11PM +, Vince Weaver wrote: > On Wed, 30 Oct 2013, Peter Zijlstra wrote: > > The below code should deal with both cases I think -- completely > > untested. > > Uncompiled too I guess? > > kernel/events/core.c: In function ‘perf_event_period’: > kernel/events/core

Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-30 Thread Vince Weaver
On Wed, 30 Oct 2013, Peter Zijlstra wrote: > Right, it was one of those interfaces that people claimed were > absolutely required so I implemented them but then nobody actually tried > using them for a long while :-( Well, the initial perf_event code drop was a big huge new interface without muc

Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-30 Thread Stephane Eranian
On Wed, Oct 30, 2013 at 10:56 AM, Peter Zijlstra wrote: > On Tue, Oct 29, 2013 at 11:36:52AM -0400, Vince Weaver wrote: >> On Tue, 29 Oct 2013, Peter Zijlstra wrote: >> > On Tue, Oct 29, 2013 at 04:28:10AM +, Will Deacon wrote: >> > > >> > > I can CC LKML on ARM perf patches if you think it wi

Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-30 Thread Peter Zijlstra
On Tue, Oct 29, 2013 at 11:36:52AM -0400, Vince Weaver wrote: > On Tue, 29 Oct 2013, Peter Zijlstra wrote: > > On Tue, Oct 29, 2013 at 04:28:10AM +, Will Deacon wrote: > > > > > > I can CC LKML on ARM perf patches if you think it will help, but all PMU > > > backend patches go via their respec

Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-29 Thread Vince Weaver
On Tue, 29 Oct 2013, Peter Zijlstra wrote: > On Tue, Oct 29, 2013 at 04:28:10AM +, Will Deacon wrote: > > > > I can CC LKML on ARM perf patches if you think it will help, but all PMU > > backend patches go via their respective arch trees afaict. > > Just those that change user visible semanti

Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-29 Thread Peter Zijlstra
On Tue, Oct 29, 2013 at 04:28:10AM +, Will Deacon wrote: > On Mon, Oct 28, 2013 at 02:07:48PM +, Vince Weaver wrote: > > It's also a shame this change apprently didn't hit the linux-kernel list > > as far as I can tell. I do my best to try to note all of the perf > > ABI-related changes

Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-28 Thread Will Deacon
On Mon, Oct 28, 2013 at 02:07:48PM +, Vince Weaver wrote: > It's also a shame this change apprently didn't hit the linux-kernel list > as far as I can tell. I do my best to try to note all of the perf > ABI-related changes there, but if things like this are going to start > getting merged i

Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-28 Thread Vince Weaver
On Mon, 28 Oct 2013, Will Deacon wrote: > This was in response to complaints from both internal users and people on > public lists: > > > http://www.mail-archive.com/perfmon2-devel@lists.sourceforge.net/msg02657.html > > I believe the scenario was something like: > > (1) An instruction coun

Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-28 Thread Will Deacon
On Mon, Oct 28, 2013 at 10:00:49AM +, Peter Zijlstra wrote: > On Mon, Oct 28, 2013 at 08:57:00AM +, Will Deacon wrote: > > > Should other architectures be updated to? I just wanted to find out the > > > rationale for this before I update the manpage to reflect the difference > > > in beh

Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-28 Thread Peter Zijlstra
On Mon, Oct 28, 2013 at 08:57:00AM +, Will Deacon wrote: > > Should other architectures be updated to? I just wanted to find out the > > rationale for this before I update the manpage to reflect the difference > > in behaviors between architectures. > > I don't want to be the `oddball' arch

Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-28 Thread Will Deacon
On Mon, Oct 28, 2013 at 02:37:46AM +, Vince Weaver wrote: > Hello Hi Vince, > it was pointed out to me that in the 3.7 kernel (more specifically, > 3581fe0ef37ce12ac7a4f74831168352ae848edc ) a change was made in the > ARM architecture to change how PERF_EVENT_IOC_PERIOD is handled. > > Unlik

perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

2013-10-27 Thread Vince Weaver
Hello it was pointed out to me that in the 3.7 kernel (more specifically, 3581fe0ef37ce12ac7a4f74831168352ae848edc ) a change was made in the ARM architecture to change how PERF_EVENT_IOC_PERIOD is handled. Unlike other architectures, post-3.7 ARM updates the period right away rather than waitin