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Message-ID: <CAP-5=fWnOGD7CHYeq0Uino4eHte2WP5Pxz9t4YOtvgxrq-_muA@mail.gmail.com>
Date: Sat, 14 Jan 2023 14:15:40 -0800
From: Ian Rogers <irogers@...gle.com>
To: Jing Zhang <renyu.zj@...ux.alibaba.com>
Cc: John Garry <john.g.garry@...cle.com>,
Xing Zhengjun <zhengjun.xing@...ux.intel.com>,
Will Deacon <will@...nel.org>,
James Clark <james.clark@....com>,
Mike Leach <mike.leach@...aro.org>,
Leo Yan <leo.yan@...aro.org>,
linux-arm-kernel@...ts.infradead.org,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Andrew Kilroy <andrew.kilroy@....com>,
Shuai Xue <xueshuai@...ux.alibaba.com>,
Zhuo Song <zhuo.song@...ux.alibaba.com>
Subject: Re: [PATCH v7 1/9] perf pmu: Add #slots literal support for arm64
On Fri, Jan 13, 2023 at 1:22 AM Jing Zhang <renyu.zj@...ux.alibaba.com> wrote:
>
> The slots in each architecture may be different, so add #slots literal
> to obtain the slots of different architectures, and the #slots can be
> applied in the metric. Currently, The #slots just support for arm64,
> and other architectures will return NAN.
>
> On arm64, the value of slots is from the register PMMIR_EL1.SLOT, which
> I can read in /sys/bus/event_source/device/armv8_pmuv3_*/caps/slots.
> PMMIR_EL1.SLOT might read as zero if the PMU version is lower than
> ID_AA64DFR0_EL1_PMUVer_V3P4 or the STALL_SLOT event is not implemented.
>
> Signed-off-by: Jing Zhang <renyu.zj@...ux.alibaba.com>
> ---
> tools/perf/arch/arm64/util/pmu.c | 34 ++++++++++++++++++++++++++++++++--
> tools/perf/util/expr.c | 5 +++++
> tools/perf/util/pmu.c | 6 ++++++
> tools/perf/util/pmu.h | 1 +
> 4 files changed, 44 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/arch/arm64/util/pmu.c b/tools/perf/arch/arm64/util/pmu.c
> index 477e513..5f8667b 100644
> --- a/tools/perf/arch/arm64/util/pmu.c
> +++ b/tools/perf/arch/arm64/util/pmu.c
> @@ -3,8 +3,9 @@
> #include <internal/cpumap.h>
> #include "../../../util/cpumap.h"
> #include "../../../util/pmu.h"
> +#include <api/fs/fs.h>
>
> -const struct pmu_events_table *pmu_events_table__find(void)
> +static struct perf_pmu *pmu_core__find_same(void)
I'm not sure "find_same" is the best name here. I suspect it should be
"find_core_pmu" which would agree with is_arm_pmu_core. Unfortunately
"core" has become an overloaded term sometimes used interchangeably
with CPU, hyperthread or SMT thread, it was a model name for Intel and
it is used to distinguish a set of SMT threads running together from a
single one. Anyway, for consistency I think perf_pmu__find_core_pmu is
the most appropriate name (or pmu__find_core_pmu, I'm not sure why we
get the extra perf_ prefix sometimes, in general that indicates the
functionality is in libperf).
Aside from that, lgtm. Thanks,
Ian
> {
> struct perf_pmu *pmu = NULL;
>
> @@ -19,8 +20,37 @@ const struct pmu_events_table *pmu_events_table__find(void)
> if (pmu->cpus->nr != cpu__max_cpu().cpu)
> return NULL;
>
> - return perf_pmu__find_table(pmu);
> + return pmu;
> }
>
> return NULL;
> }
> +
> +const struct pmu_events_table *pmu_events_table__find(void)
> +{
> + struct perf_pmu *pmu = pmu_core__find_same();
> +
> + if (pmu)
> + return perf_pmu__find_table(pmu);
> +
> + return NULL;
> +}
> +
> +double perf_pmu__cpu_slots_per_cycle(void)
> +{
> + char path[PATH_MAX];
> + unsigned long long slots = 0;
> + struct perf_pmu *pmu = pmu_core__find_same();
> +
> + if (pmu) {
> + scnprintf(path, PATH_MAX,
> + EVENT_SOURCE_DEVICE_PATH "%s/caps/slots", pmu->name);
> + /*
> + * The value of slots is not greater than 32 bits, but sysfs__read_int
> + * can't read value with 0x prefix, so use sysfs__read_ull instead.
> + */
> + sysfs__read_ull(path, &slots);
> + }
> +
> + return (double)slots;
> +}
> diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
> index 00dcde3..9d3076a 100644
> --- a/tools/perf/util/expr.c
> +++ b/tools/perf/util/expr.c
> @@ -19,6 +19,7 @@
> #include <linux/zalloc.h>
> #include <ctype.h>
> #include <math.h>
> +#include "pmu.h"
>
> #ifdef PARSER_DEBUG
> extern int expr_debug;
> @@ -448,6 +449,10 @@ double expr__get_literal(const char *literal, const struct expr_scanner_ctx *ctx
> result = topology->core_cpus_lists;
> goto out;
> }
> + if (!strcmp("#slots", literal)) {
> + result = perf_pmu__cpu_slots_per_cycle() ?: NAN;
> + goto out;
> + }
>
> pr_err("Unrecognized literal '%s'", literal);
> out:
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 2bdeb89..cbb4fbf 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -19,6 +19,7 @@
> #include <regex.h>
> #include <perf/cpumap.h>
> #include <fnmatch.h>
> +#include <math.h>
> #include "debug.h"
> #include "evsel.h"
> #include "pmu.h"
> @@ -1993,3 +1994,8 @@ int perf_pmu__cpus_match(struct perf_pmu *pmu, struct perf_cpu_map *cpus,
> *ucpus_ptr = unmatched_cpus;
> return 0;
> }
> +
> +double __weak perf_pmu__cpu_slots_per_cycle(void)
> +{
> + return NAN;
> +}
> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> index 69ca000..fd414ba 100644
> --- a/tools/perf/util/pmu.h
> +++ b/tools/perf/util/pmu.h
> @@ -259,4 +259,5 @@ int perf_pmu__cpus_match(struct perf_pmu *pmu, struct perf_cpu_map *cpus,
>
> char *pmu_find_real_name(const char *name);
> char *pmu_find_alias_name(const char *name);
> +double perf_pmu__cpu_slots_per_cycle(void);
> #endif /* __PMU_H */
> --
> 1.8.3.1
>
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