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Date: Thu, 1 Sep 2022 08:42:05 -0400
From: "Liang, Kan" <kan.liang@...ux.intel.com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: peterz@...radead.org, acme@...nel.org, mingo@...hat.com,
eranian@...gle.com, mpe@...erman.id.au,
linux-kernel@...r.kernel.org, ak@...ux.intel.com,
andreas.kogler.0x@...il.com, atrajeev@...ux.vnet.ibm.com,
ravi.bangoria@....com
Subject: Re: [PATCH 3/6] perf: Use sample_flags for branch stack
On 2022-08-31 6:47 p.m., Namhyung Kim wrote:
> On Wed, Aug 31, 2022 at 07:55:11AM -0700, kan.liang@...ux.intel.com wrote:
>> From: Kan Liang <kan.liang@...ux.intel.com>
>>
>> Use the new sample_flags to indicate whether the branch stack is filled
>> by the PMU driver.
>>
>> Remove the br_stack from the perf_sample_data_init() to minimize the number
>> of cache lines touched.
>>
>> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
>> ---
>> arch/powerpc/perf/core-book3s.c | 1 +
>> arch/x86/events/core.c | 4 +++-
>> arch/x86/events/intel/core.c | 4 +++-
>> arch/x86/events/intel/ds.c | 5 ++++-
>> include/linux/perf_event.h | 4 ++--
>> kernel/events/core.c | 4 ++--
>> 6 files changed, 15 insertions(+), 7 deletions(-)
>
> Looks like you need to update AMD LBR code in amd_pmu_v2_handle_irq().
Right, the patch is on the top of the 6.0-rc, which doesn't include the
AMD LBR code yet. I will re-base on Peter's perf/core.
Thanks,
Kan
>
> Thanks,
> Namhyung
>
>>
>> diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
>> index 13919eb96931..1ad1efdb33f9 100644
>> --- a/arch/powerpc/perf/core-book3s.c
>> +++ b/arch/powerpc/perf/core-book3s.c
>> @@ -2297,6 +2297,7 @@ static void record_and_restart(struct perf_event *event, unsigned long val,
>> cpuhw = this_cpu_ptr(&cpu_hw_events);
>> power_pmu_bhrb_read(event, cpuhw);
>> data.br_stack = &cpuhw->bhrb_stack;
>> + data.sample_flags |= PERF_SAMPLE_BRANCH_STACK;
>> }
>>
>> if (event->attr.sample_type & PERF_SAMPLE_DATA_SRC &&
>> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
>> index f969410d0c90..bb34a28fa71b 100644
>> --- a/arch/x86/events/core.c
>> +++ b/arch/x86/events/core.c
>> @@ -1714,8 +1714,10 @@ int x86_pmu_handle_irq(struct pt_regs *regs)
>>
>> perf_sample_data_init(&data, 0, event->hw.last_period);
>>
>> - if (has_branch_stack(event))
>> + if (has_branch_stack(event)) {
>> data.br_stack = &cpuc->lbr_stack;
>> + data.sample_flags |= PERF_SAMPLE_BRANCH_STACK;
>> + }
>>
>> if (perf_event_overflow(event, &data, regs))
>> x86_pmu_stop(event, 0);
>> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
>> index 4fce2bdbbf87..36f95894dd1c 100644
>> --- a/arch/x86/events/intel/core.c
>> +++ b/arch/x86/events/intel/core.c
>> @@ -3004,8 +3004,10 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status)
>>
>> perf_sample_data_init(&data, 0, event->hw.last_period);
>>
>> - if (has_branch_stack(event))
>> + if (has_branch_stack(event)) {
>> data.br_stack = &cpuc->lbr_stack;
>> + data.sample_flags |= PERF_SAMPLE_BRANCH_STACK;
>> + }
>>
>> if (perf_event_overflow(event, &data, regs))
>> x86_pmu_stop(event, 0);
>> diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
>> index 3af24c4891fb..d5f3007af59d 100644
>> --- a/arch/x86/events/intel/ds.c
>> +++ b/arch/x86/events/intel/ds.c
>> @@ -1645,8 +1645,10 @@ static void setup_pebs_fixed_sample_data(struct perf_event *event,
>> data->sample_flags |= PERF_SAMPLE_TIME;
>> }
>>
>> - if (has_branch_stack(event))
>> + if (has_branch_stack(event)) {
>> data->br_stack = &cpuc->lbr_stack;
>> + data->sample_flags |= PERF_SAMPLE_BRANCH_STACK;
>> + }
>> }
>>
>> static void adaptive_pebs_save_regs(struct pt_regs *regs,
>> @@ -1796,6 +1798,7 @@ static void setup_pebs_adaptive_sample_data(struct perf_event *event,
>> if (has_branch_stack(event)) {
>> intel_pmu_store_pebs_lbrs(lbr);
>> data->br_stack = &cpuc->lbr_stack;
>> + data->sample_flags |= PERF_SAMPLE_BRANCH_STACK;
>> }
>> }
>>
>> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
>> index b0ebbb1377b9..2aec1765b3d5 100644
>> --- a/include/linux/perf_event.h
>> +++ b/include/linux/perf_event.h
>> @@ -1010,7 +1010,6 @@ struct perf_sample_data {
>> u64 sample_flags;
>> u64 addr;
>> struct perf_raw_record *raw;
>> - struct perf_branch_stack *br_stack;
>> u64 period;
>> union perf_sample_weight weight;
>> u64 txn;
>> @@ -1020,6 +1019,8 @@ struct perf_sample_data {
>> * The other fields, optionally {set,used} by
>> * perf_{prepare,output}_sample().
>> */
>> + struct perf_branch_stack *br_stack;
>> +
>> u64 type;
>> u64 ip;
>> struct {
>> @@ -1060,7 +1061,6 @@ static inline void perf_sample_data_init(struct perf_sample_data *data,
>> data->sample_flags = 0;
>> data->addr = addr;
>> data->raw = NULL;
>> - data->br_stack = NULL;
>> data->period = period;
>> data->weight.full = 0;
>> data->data_src.val = PERF_MEM_NA;
>> diff --git a/kernel/events/core.c b/kernel/events/core.c
>> index c9b9cb79231a..104c0c9f4e6f 100644
>> --- a/kernel/events/core.c
>> +++ b/kernel/events/core.c
>> @@ -7052,7 +7052,7 @@ void perf_output_sample(struct perf_output_handle *handle,
>> }
>>
>> if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
>> - if (data->br_stack) {
>> + if (data->sample_flags & PERF_SAMPLE_BRANCH_STACK) {
>> size_t size;
>>
>> size = data->br_stack->nr
>> @@ -7358,7 +7358,7 @@ void perf_prepare_sample(struct perf_event_header *header,
>>
>> if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
>> int size = sizeof(u64); /* nr */
>> - if (data->br_stack) {
>> + if (data->sample_flags & PERF_SAMPLE_BRANCH_STACK) {
>> if (perf_sample_save_hw_index(event))
>> size += sizeof(u64);
>>
>> --
>> 2.35.1
>>
>>
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