Re: [PATCH V6] perf: Add PERF_SAMPLE_PHYS_ADDR

From: Arnaldo Carvalho de Melo
Date: Thu Aug 31 2017 - 12:44:45 EST


Em Wed, Aug 23, 2017 at 10:00:37AM -0700, Stephane Eranian escreveu:
> On Wed, Aug 23, 2017 at 7:39 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> > On Wed, Aug 23, 2017 at 04:33:08PM +0200, Peter Zijlstra wrote:
> >> > @@ -6145,6 +6183,9 @@ void perf_prepare_sample(struct perf_event_header *header,
> >> >
> >> > header->size += size;
> >> > }
> >> > +
> >> > + if (sample_type & PERF_SAMPLE_PHYS_ADDR)
> >> > + data->phys_addr = perf_virt_to_phys(data->addr);
> >>
> >> Only problem with this now is that it requires SAMPLE_ADDR to also be
> >> set in order to obtain data->addr.
> >>
> >> Either fix all to set data->attr for (SAMPLE_ADDR || SAMPLE_PHYS_ADDR)
> >> or mandate SAMPLE_ADDR when SAMPLE_PHYS_ADDR.
> >
> > I think the former suggestion is better, as it allows for smaller
> > samples.
>
> Agreed. I may only care about physical addresses, so SAMPLE_PHYS_ADDR
> should suffice from the user.
> The kernel must save the virtual address in data->addr, and then convert it.

Stephane, have you took the time to test this together with Kan's latest
patchkit for tools/perf? v2? If so can I have your Tested-by or just an
Acked-by?

Thanks,

- Arnaldo