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Date: Tue, 19 Nov 2019 11:00:00 -0800
From: Stephane Eranian <eranian@...gle.com>
To: "Liang, Kan" <kan.liang@...ux.intel.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Ingo Molnar <mingo@...nel.org>,
LKML <linux-kernel@...r.kernel.org>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
vitaly.slobodskoy@...el.com, pavel.gerasimov@...el.com,
Andi Kleen <ak@...ux.intel.com>,
Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH V4 03/13] perf tools: Support new branch sample type for
LBR TOS
On Tue, Nov 19, 2019 at 6:35 AM <kan.liang@...ux.intel.com> wrote:
>
> From: Kan Liang <kan.liang@...ux.intel.com>
>
> Support new branch sample type for LBR TOS.
>
> Enable LBR_TOS by default in LBR call stack mode.
> If kernel doesn't support the sample type, switching it off.
>
> Add a new branch options "tos" for the new branch sample type.
> The branch sample type is 64 bits. Change int to u64 for mode in
> struct branch_mode and bit in struct bit_names.
>
> Set tos to -1ULL if the LBR TOS information is unavailable.
>
> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
> ---
> tools/include/uapi/linux/perf_event.h | 16 ++++++++++++++--
> tools/perf/util/event.h | 1 +
> tools/perf/util/evsel.c | 20 +++++++++++++++++---
> tools/perf/util/evsel.h | 6 ++++++
> tools/perf/util/parse-branch-options.c | 3 ++-
> tools/perf/util/perf_event_attr_fprintf.c | 3 ++-
> 6 files changed, 42 insertions(+), 7 deletions(-)
>
> diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
> index bb7b271397a6..c2da61c9ace7 100644
> --- a/tools/include/uapi/linux/perf_event.h
> +++ b/tools/include/uapi/linux/perf_event.h
> @@ -180,7 +180,10 @@ enum perf_branch_sample_type_shift {
>
> PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT = 16, /* save branch type */
>
> - PERF_SAMPLE_BRANCH_MAX_SHIFT /* non-ABI */
> + PERF_SAMPLE_BRANCH_MAX_SHIFT = 17, /* non-ABI */
> +
> + /* PMU specific */
No! You must abstract this.
> + PERF_SAMPLE_BRANCH_LBR_TOS_SHIFT = 63, /* save LBR TOS */
> };
>
I don't like this because this is too Intel specific.
What is the meaning of this field? You need a clear definition so it can be used
with other PERF_SAMPLE_BRANCH_* implementations.
>
> enum perf_branch_sample_type {
> @@ -208,8 +211,13 @@ enum perf_branch_sample_type {
> 1U << PERF_SAMPLE_BRANCH_TYPE_SAVE_SHIFT,
>
> PERF_SAMPLE_BRANCH_MAX = 1U << PERF_SAMPLE_BRANCH_MAX_SHIFT,
> +
> + PERF_SAMPLE_BRANCH_LBR_TOS = 1ULL << PERF_SAMPLE_BRANCH_LBR_TOS_SHIFT,
> };
>
> +#define PERF_SAMPLE_BRANCH_MASK ((PERF_SAMPLE_BRANCH_MAX - 1) |\
> + PERF_SAMPLE_BRANCH_LBR_TOS)
> +
> /*
> * Common flow change classification
> */
> @@ -849,7 +857,11 @@ enum perf_event_type {
> * char data[size];}&& PERF_SAMPLE_RAW
> *
> * { u64 nr;
> - * { u64 from, to, flags } lbr[nr];} && PERF_SAMPLE_BRANCH_STACK
> + * { u64 from, to, flags } lbr[nr];
> + *
> + * # only available if PERF_SAMPLE_BRANCH_LBR_TOS is set
> + * u64 tos;
> + * } && PERF_SAMPLE_BRANCH_STACK
> *
> * { u64 abi; # enum perf_sample_regs_abi
> * u64 regs[weight(mask)]; } && PERF_SAMPLE_REGS_USER
> diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
> index a0a0c91cde4a..98794758546b 100644
> --- a/tools/perf/util/event.h
> +++ b/tools/perf/util/event.h
> @@ -130,6 +130,7 @@ struct perf_sample {
> u32 raw_size;
> u64 data_src;
> u64 phys_addr;
> + u64 lbr_tos;
> u32 flags;
> u16 insn_len;
> u8 cpumode;
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 1bf60f325608..b19669eb4437 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -712,7 +712,8 @@ static void __perf_evsel__config_callchain(struct evsel *evsel,
> attr->branch_sample_type = PERF_SAMPLE_BRANCH_USER |
> PERF_SAMPLE_BRANCH_CALL_STACK |
> PERF_SAMPLE_BRANCH_NO_CYCLES |
> - PERF_SAMPLE_BRANCH_NO_FLAGS;
> + PERF_SAMPLE_BRANCH_NO_FLAGS |
> + PERF_SAMPLE_BRANCH_LBR_TOS;
> }
> } else
> pr_warning("Cannot use LBR callstack with branch stack. "
> @@ -763,7 +764,8 @@ perf_evsel__reset_callgraph(struct evsel *evsel,
> if (param->record_mode == CALLCHAIN_LBR) {
> perf_evsel__reset_sample_bit(evsel, BRANCH_STACK);
> attr->branch_sample_type &= ~(PERF_SAMPLE_BRANCH_USER |
> - PERF_SAMPLE_BRANCH_CALL_STACK);
> + PERF_SAMPLE_BRANCH_CALL_STACK |
> + PERF_SAMPLE_BRANCH_LBR_TOS);
> }
> if (param->record_mode == CALLCHAIN_DWARF) {
> perf_evsel__reset_sample_bit(evsel, REGS_USER);
> @@ -1641,6 +1643,8 @@ int evsel__open(struct evsel *evsel, struct perf_cpu_map *cpus,
> evsel->core.attr.ksymbol = 0;
> if (perf_missing_features.bpf)
> evsel->core.attr.bpf_event = 0;
> + if (perf_missing_features.lbr_tos)
> + evsel->core.attr.branch_sample_type &= ~PERF_SAMPLE_BRANCH_LBR_TOS;
> retry_sample_id:
> if (perf_missing_features.sample_id_all)
> evsel->core.attr.sample_id_all = 0;
> @@ -1752,7 +1756,12 @@ int evsel__open(struct evsel *evsel, struct perf_cpu_map *cpus,
> * Must probe features in the order they were added to the
> * perf_event_attr interface.
> */
> - if (!perf_missing_features.aux_output && evsel->core.attr.aux_output) {
> + if (!perf_missing_features.lbr_tos &&
> + (evsel->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_LBR_TOS)) {
> + perf_missing_features.lbr_tos = true;
> + pr_debug2("switching off LBR TOS support\n");
> + goto fallback_missing_features;
> + } else if (!perf_missing_features.aux_output && evsel->core.attr.aux_output) {
> perf_missing_features.aux_output = true;
> pr_debug2_peo("Kernel has no attr.aux_output support, bailing out\n");
> goto out_close;
> @@ -2129,6 +2138,11 @@ int perf_evsel__parse_sample(struct evsel *evsel, union perf_event *event,
> sz = data->branch_stack->nr * sizeof(struct branch_entry);
> OVERFLOW_CHECK(array, sz, max_size);
> array = (void *)array + sz;
> +
> + if (perf_evsel__has_lbr_tos(evsel))
> + data->lbr_tos = *array++;
> + else
> + data->lbr_tos = -1ULL;
> }
>
> if (type & PERF_SAMPLE_REGS_USER) {
> diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> index ddc5ee6f6592..43a9fd83f791 100644
> --- a/tools/perf/util/evsel.h
> +++ b/tools/perf/util/evsel.h
> @@ -115,6 +115,7 @@ struct perf_missing_features {
> bool ksymbol;
> bool bpf;
> bool aux_output;
> + bool lbr_tos;
> };
>
> extern struct perf_missing_features perf_missing_features;
> @@ -377,6 +378,11 @@ for ((_evsel) = _leader; \
> (_evsel) && (_evsel)->leader == (_leader); \
> (_evsel) = list_entry((_evsel)->core.node.next, struct evsel, core.node))
>
> +static inline bool perf_evsel__has_lbr_tos(const struct evsel *evsel)
> +{
> + return evsel->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_LBR_TOS;
> +}
> +
> static inline bool perf_evsel__has_branch_callstack(const struct evsel *evsel)
> {
> return evsel->core.attr.branch_sample_type & PERF_SAMPLE_BRANCH_CALL_STACK;
> diff --git a/tools/perf/util/parse-branch-options.c b/tools/perf/util/parse-branch-options.c
> index bb4aa88c50a8..ce8b9ffc0663 100644
> --- a/tools/perf/util/parse-branch-options.c
> +++ b/tools/perf/util/parse-branch-options.c
> @@ -13,7 +13,7 @@
>
> struct branch_mode {
> const char *name;
> - int mode;
> + u64 mode;
> };
>
> static const struct branch_mode branch_modes[] = {
> @@ -32,6 +32,7 @@ static const struct branch_mode branch_modes[] = {
> BRANCH_OPT("call", PERF_SAMPLE_BRANCH_CALL),
> BRANCH_OPT("save_type", PERF_SAMPLE_BRANCH_TYPE_SAVE),
> BRANCH_OPT("stack", PERF_SAMPLE_BRANCH_CALL_STACK),
> + BRANCH_OPT("tos", PERF_SAMPLE_BRANCH_LBR_TOS),
> BRANCH_END
> };
>
> diff --git a/tools/perf/util/perf_event_attr_fprintf.c b/tools/perf/util/perf_event_attr_fprintf.c
> index d4ad3f04923a..3411b67ea92a 100644
> --- a/tools/perf/util/perf_event_attr_fprintf.c
> +++ b/tools/perf/util/perf_event_attr_fprintf.c
> @@ -8,7 +8,7 @@
> #include "util/evsel_fprintf.h"
>
> struct bit_names {
> - int bit;
> + u64 bit;
> const char *name;
> };
>
> @@ -50,6 +50,7 @@ static void __p_branch_sample_type(char *buf, size_t size, u64 value)
> bit_name(ABORT_TX), bit_name(IN_TX), bit_name(NO_TX),
> bit_name(COND), bit_name(CALL_STACK), bit_name(IND_JUMP),
> bit_name(CALL), bit_name(NO_FLAGS), bit_name(NO_CYCLES),
> + bit_name(LBR_TOS),
> { .name = NULL, }
> };
> #undef bit_name
> --
> 2.17.1
>
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