Re: [patch/rfc] perf on raspberry-pi without overflow interrupt

From: Will Deacon
Date: Wed May 07 2014 - 13:30:23 EST


Hi Vince,

On Mon, Feb 24, 2014 at 03:37:11PM +0000, Vince Weaver wrote:
> On Mon, 24 Feb 2014, Will Deacon wrote:
> > On Fri, Jan 17, 2014 at 05:45:04AM +0000, Vince Weaver wrote:
> > > On Thu, 16 Jan 2014, Peter Zijlstra wrote:
> > >
> > > > Yeah I suppose we could do something like that. Maybe something like:
> > > >
> > > > # cat /sys/bus/event_source/devices/cpu/flags
> > > > int precise filter
> > >
> > > wouldn't that violate the "one value per file" rule?
> > >
> > > I guess we could also stick it in the mmap page somewhere, as tools like
> > > PAPI already have to check there for things like rdpmc support.
> > >
> > >
> > > Anyway, here's a first pass at a generic fix for this issue. I'm sure the
> > > code is pretty horrible, I don't usually mess with the perf code at this
> > > level. I haven't tested yet as it touched enough files that the rasp-pi
> > > is going to take a few hours to finish compiling.
> > >
> > > Am I on the right track, or totally off here?
> >
> > Where did we get to with this? If the generic changes are going to take some
> > time, I'm happy to take a temporary (non-invasive) fix in the ARM backend while
> > you sort out the core.
>
> OK, let me revisit the patches. The last set of generic ones I sent out
> actually was broken on ARM and I've been meaning to straighten things out
> and send a proper follow up patch set but got distracted by other perf
> related issues.

Any luck with this? I just got (another) report of a PMU with borked
interrupts, so a fix would be great if you've got one.

Will
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