Messages in this thread Patch in this message | | | Date | Wed, 24 Aug 2022 11:27:53 +0200 | From | Peter Zijlstra <> | Subject | Re: [BUG] perf/x86/intel/pebs: PEBS timestamps overwritten |
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Should be 3 patches at the very least I think, the first one introducing the new field and then follow up patches making use of it.
And yes as Ravi mentions there's the CALLCHAIN_EARLY hack that could be cleaned up as well, making it 4 or something.
On Fri, Aug 05, 2022 at 09:36:37AM -0400, Liang, Kan wrote:
> diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c > index 34be3bc5151a..a2c26eaeb0d9 100644 > --- a/arch/x86/events/intel/ds.c > +++ b/arch/x86/events/intel/ds.c > @@ -1687,8 +1687,10 @@ static void setup_pebs_fixed_sample_data(struct > perf_event *event, > * We can only do this for the default trace clock. > */ > if (x86_pmu.intel_cap.pebs_format >= 3 && > - event->attr.use_clockid == 0) > + event->attr.use_clockid == 0) {
Indent fail; please add: 'set cino=(0:0' to your .vimrc or figure out the equivalent for your editor of choice.
> data->time = native_sched_clock_from_tsc(pebs->tsc); > + data->flags |= PERF_SAMPLE_DATA_TIME; > + } > > if (has_branch_stack(event)) > data->br_stack = &cpuc->lbr_stack;
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index da759560eec5..33054bf31fc1 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -999,6 +999,7 @@ int perf_event_read_local(struct perf_event *event, > u64 *value, > extern u64 perf_event_read_value(struct perf_event *event, > u64 *enabled, u64 *running); > > +#define PERF_SAMPLE_DATA_TIME 0x1 > > struct perf_sample_data { > /* > @@ -1012,6 +1013,7 @@ struct perf_sample_data { > union perf_sample_weight weight; > u64 txn; > union perf_mem_data_src data_src; > + u64 flags; > > /* > * The other fields, optionally {set,used} by
How about we call that 'sample_flags' instead and use PERF_SAMPLE_* as we already have, something like so:
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index ee8b9ecdc03b..b0ebbb1377b9 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1007,6 +1007,7 @@ struct perf_sample_data { * Fields set by perf_sample_data_init(), group so as to * minimize the cachelines touched. */ + u64 sample_flags; u64 addr; struct perf_raw_record *raw; struct perf_branch_stack *br_stack; @@ -1056,6 +1057,7 @@ static inline void perf_sample_data_init(struct perf_sample_data *data, u64 addr, u64 period) { /* remaining struct members initialized in perf_prepare_sample() */ + data->sample_flags = 0; data->addr = addr; data->raw = NULL; data->br_stack = NULL; diff --git a/kernel/events/core.c b/kernel/events/core.c index 2621fd24ad26..fed447f59024 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6792,15 +6792,21 @@ static void perf_aux_sample_output(struct perf_event *event, ring_buffer_put(rb); } -static void __perf_event_header__init_id(struct perf_event_header *header, - struct perf_sample_data *data, - struct perf_event *event) +static u64 __perf_event_header__init_id(struct perf_event_header *header, + struct perf_sample_data *data, + struct perf_event *event) { u64 sample_type = event->attr.sample_type; data->type = sample_type; header->size += event->id_header_size; + /* + * Clear the sample flags that have already been done by the + * PMU driver. + */ + sample_type &= ~data->sample_flags; + if (sample_type & PERF_SAMPLE_TID) { /* namespace issues */ data->tid_entry.pid = perf_event_pid(event, current); @@ -6820,6 +6826,8 @@ static void __perf_event_header__init_id(struct perf_event_header *header, data->cpu_entry.cpu = raw_smp_processor_id(); data->cpu_entry.reserved = 0; } + + return sample_type; } void perf_event_header__init_id(struct perf_event_header *header, @@ -7302,7 +7310,7 @@ void perf_prepare_sample(struct perf_event_header *header, struct perf_event *event, struct pt_regs *regs) { - u64 sample_type = event->attr.sample_type; + u64 sample_type; header->type = PERF_RECORD_SAMPLE; header->size = sizeof(*header) + event->header_size; @@ -7310,7 +7318,7 @@ void perf_prepare_sample(struct perf_event_header *header, header->misc = 0; header->misc |= perf_misc_flags(regs); - __perf_event_header__init_id(header, data, event); + sample_type = __perf_event_header__init_id(header, data, event); if (sample_type & (PERF_SAMPLE_IP | PERF_SAMPLE_CODE_PAGE_SIZE)) data->ip = perf_instruction_pointer(regs);
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