Re: [PATCH 1/3] perf intel-pt: Fix recording PEBS-via-PT with registers

[Arnaldo Carvalho de Melo]

Em Fri, Jul 03, 2020 at 08:25:03AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Tue, Jun 30, 2020 at 04:39:33PM +0300, Adrian Hunter escreveu:
> > When recording PEBS-via-PT, the kernel will not accept the intel_pt event
> > with register sampling e.g.
> > 
> >  # perf record --kcore -c 10000 -e '{intel_pt/branch=0/,branch-loads/aux-output/ppp}' -I -- ls -l
> >  Error:
> >  intel_pt/branch=0/: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat'
> > 
> > Fix by suppressing register sampling on the intel_pt evsel.
> 
> Next time please inform what is the hardware that supports PEBS-via-PT,
> I tried this on a:
> 
> [    0.245654] smpboot: CPU0: Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz (family: 0x6, model: 0x8e, stepping: 0xa)
> [    0.245791] Performance Events: PEBS fmt3+, Skylake events, 32-deep LBR, full-width counters, Intel PMU driver.

Also:

[acme@quaco perf]$ uname -a
Linux quaco 5.8.0-rc3+ #2 SMP Tue Jun 30 09:47:17 -03 2020 x86_64 x86_64 x86_64 GNU/Linux
 
> And even after this fix I get:
> 
> [root@quaco ~]# perf record --kcore -c 10000 -e '{intel_pt/branch=0/,branch-loads/aux-output/ppp}' -I -- ls -l
> Error:
> branch-loads: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat'
> [root@quaco ~]#
> 
> Further details:
> 
> [root@quaco ~]# perf record -vv --kcore -c 10000 -e '{intel_pt/branch=0/,branch-loads/aux-output/ppp}' -I -- ls -l
> Using CPUID GenuineIntel-6-8E-A
> intel_pt default config: tsc,mtc,mtc_period=3,psb_period=3,pt,branch
> Attempting to add event pmu 'intel_pt' with 'branch,' that may result in non-fatal errors
> After aliases, add event pmu 'intel_pt' with 'branch,' that may result in non-fatal errors
> nr_cblocks: 0
> affinity: SYS
> mmap flush: 1
> comp level: 0
> ------------------------------------------------------------
> perf_event_attr:
>   type                             8
>   size                             120
>   config                           0x300c601
>   { sample_period, sample_freq }   10000
>   sample_type                      IP|TID|TIME|CPU|IDENTIFIER
>   read_format                      ID
>   disabled                         1
>   inherit                          1
>   enable_on_exec                   1
>   sample_id_all                    1
>   exclude_guest                    1
> ------------------------------------------------------------
> sys_perf_event_open: pid 11131  cpu 0  group_fd -1  flags 0x8 = 5
> sys_perf_event_open: pid 11131  cpu 1  group_fd -1  flags 0x8 = 6
> sys_perf_event_open: pid 11131  cpu 2  group_fd -1  flags 0x8 = 7
> sys_perf_event_open: pid 11131  cpu 3  group_fd -1  flags 0x8 = 9
> sys_perf_event_open: pid 11131  cpu 4  group_fd -1  flags 0x8 = 10
> sys_perf_event_open: pid 11131  cpu 5  group_fd -1  flags 0x8 = 11
> sys_perf_event_open: pid 11131  cpu 6  group_fd -1  flags 0x8 = 12
> sys_perf_event_open: pid 11131  cpu 7  group_fd -1  flags 0x8 = 13
> ------------------------------------------------------------
> perf_event_attr:
>   type                             3
>   size                             120
>   config                           0x5
>   { sample_period, sample_freq }   10000
>   sample_type                      IP|TID|TIME|IDENTIFIER|REGS_INTR
>   read_format                      ID
>   inherit                          1
>   precise_ip                       3
>   sample_id_all                    1
>   exclude_guest                    1
>   aux_output                       1
>   sample_regs_intr                 0xff0fff
> ------------------------------------------------------------
> sys_perf_event_open: pid 11131  cpu 0  group_fd 5  flags 0x8
> sys_perf_event_open failed, error -95
> Error:
> branch-loads: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat'
> [root@quaco ~]#
> 
> 
> 
> 
>  
> > Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> > Fixes: 9e64cefe4335b ("perf intel-pt: Process options for PEBS event synthesis")
> > ---
> >  tools/perf/arch/x86/util/intel-pt.c | 1 +
> >  tools/perf/util/evsel.c             | 4 ++--
> >  2 files changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tools/perf/arch/x86/util/intel-pt.c b/tools/perf/arch/x86/util/intel-pt.c
> > index 839ef52c1ac2..6ce451293634 100644
> > --- a/tools/perf/arch/x86/util/intel-pt.c
> > +++ b/tools/perf/arch/x86/util/intel-pt.c
> > @@ -641,6 +641,7 @@ static int intel_pt_recording_options(struct auxtrace_record *itr,
> >  			}
> >  			evsel->core.attr.freq = 0;
> >  			evsel->core.attr.sample_period = 1;
> > +			evsel->no_aux_samples = true;
> >  			intel_pt_evsel = evsel;
> >  			opts->full_auxtrace = true;
> >  		}
> > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> > index a68ac3632ae6..ef802f6d40c1 100644
> > --- a/tools/perf/util/evsel.c
> > +++ b/tools/perf/util/evsel.c
> > @@ -1014,12 +1014,12 @@ void evsel__config(struct evsel *evsel, struct record_opts *opts,
> >  	if (callchain && callchain->enabled && !evsel->no_aux_samples)
> >  		evsel__config_callchain(evsel, opts, callchain);
> >  
> > -	if (opts->sample_intr_regs) {
> > +	if (opts->sample_intr_regs && !evsel->no_aux_samples) {
> >  		attr->sample_regs_intr = opts->sample_intr_regs;
> >  		evsel__set_sample_bit(evsel, REGS_INTR);
> >  	}
> >  
> > -	if (opts->sample_user_regs) {
> > +	if (opts->sample_user_regs && !evsel->no_aux_samples) {
> >  		attr->sample_regs_user |= opts->sample_user_regs;
> >  		evsel__set_sample_bit(evsel, REGS_USER);
> >  	}
> > -- 
> > 2.17.1
> > 
> 
> -- 
> 
> - Arnaldo

-- 

- Arnaldo