Messages in this thread | | | Subject | Re: [PATCH -tip v3 2/5] perf: change perf_event_header.misc to PERF_RECORD_MISC_USER for BTS | From | Peter Zijlstra <> | Date | Thu, 11 Aug 2011 14:18:46 +0200 |
| |
On Thu, 2011-08-11 at 21:06 +0900, Akihiro Nagai wrote: > Change perf_event_headder.misc to PERF_RECORD_MISC_USER for > BTS records, because BTS traces both kernel and user spaces > nevertheless perf specifies to trace only kernel or user space.
Now I'm confused..
If BTS traces both kernel and user, the MISC bit should reflect the right state per-sample, on x86 that's easy enough to do by the address.
> --- > > arch/x86/kernel/cpu/perf_event_intel_ds.c | 8 ++++++++ > 1 files changed, 8 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c > index 1b1ef3a..323f3f0 100644 > --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c > +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c > @@ -340,6 +340,14 @@ static int intel_pmu_drain_bts_buffer(void) > */ > perf_prepare_sample(&header, &data, event, ®s); > > + /* > + * Since BTS can not trace kernel and user space separately, set
Uhm, IA32_DEBUGCTL_MSR.BTS_OFF_{OS,USR} seem to suggest it can?!
> + * PERF_RECORD_MISC_USER in header.misc to resolve both kernel and > + * user DSOs and symbols. > + */ > + header.misc &= ~PERF_RECORD_MISC_CPUMODE_MASK; > + header.misc |= PERF_RECORD_MISC_USER;
So what's wrong with something like:
header.misc |= is_kernel_address(at->from) ? PERF_RECORD_MISC_KERNEL : PERF_RECORD_MISC_USER;
> if (perf_output_begin(&handle, event, header.size * (top - at))) > return 1; > >
| |