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Date: Tue, 23 Jan 2024 21:17:41 -0800
From: Ian Rogers <irogers@...gle.com>
To: weilin.wang@...el.com
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>, Kan Liang <kan.liang@...ux.intel.com>,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
Perry Taylor <perry.taylor@...el.com>, Samantha Alt <samantha.alt@...el.com>,
Caleb Biggers <caleb.biggers@...el.com>, Mark Rutland <mark.rutland@....com>,
Yang Jihong <yangjihong1@...wei.com>
Subject: Re: [RFC PATCH v3 07/18] perf stat: Add functions to set counter
bitmaps for hardware-grouping method
On Tue, Dec 12, 2023 at 3:03 PM <weilin.wang@...el.com> wrote:
>
> From: Weilin Wang <weilin.wang@...el.com>
>
> Add metricgroup__event_info data structure to represent an event in the
> metric grouping context; the list of counters and the PMU name an event
> should be collected with.
>
> Add functions to parse event counter info from pmu-events and generate a
> list of metricgroup__event_info data to prepare grouping.
>
> Signed-off-by: Weilin Wang <weilin.wang@...el.com>
> ---
> tools/perf/util/metricgroup.c | 196 +++++++++++++++++++++++++++++++++-
> tools/perf/util/metricgroup.h | 27 +++++
> 2 files changed, 220 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> index 8d1143ee898c..24268882d355 100644
> --- a/tools/perf/util/metricgroup.c
> +++ b/tools/perf/util/metricgroup.c
> @@ -1432,6 +1432,182 @@ static int build_combined_expr_ctx(const struct list_head *metric_list,
> return ret;
> }
>
> +/**
> + * set_counter_bitmap - The counter bit mapping: [8-15,0-7], e.g. the GP0 is the
> + * 8th bit and GP7 is the 1st bit in this 16-bits bitmap. It is helpful for
> + * assigning GP4-7 before GP0-3 because some events can be collected using GP0-3
> + * only on some platforms.
> + */
> +static int set_counter_bitmap(int pos, unsigned long *bitmap)
> +{
> + if (pos >= NR_COUNTERS || pos < 0)
> + return -EINVAL;
> + if (pos <= 7)
> + pos = TRANSFER_FIRST_BYTE(pos);
> + else
> + pos = TRANSFER_SEC_BYTE(pos);
> + *bitmap |= 1ul << pos;
__set_bit may be more canonical here, in case we ever had more than 64 counters.
> + return 0;
> +}
> +
> +static int parse_fixed_counter(const char *counter,
> + unsigned long *bitmap,
> + bool *fixed)
> +{
> + int ret = -ENOENT;
> + //TODO: this pattern is different on some other platforms
> + const char *pattern = "Fixed counter ";
> + int pos = 0;
> +
> + if (!strncmp(counter, pattern, strlen(pattern))) {
> + pos = atoi(counter + strlen(pattern));
> + ret = set_counter_bitmap(pos, bitmap);
> + if (ret)
> + return ret;
> + *fixed = true;
> + return 0;
> + }
> + return ret;
> +}
It'd be nice if the counter APIs that are specific to a PMU could be
part of the struct pmu API.
> +
> +/**
> + * parse_counter - Parse event counter info from pmu-events and set up bitmap
> + * accordingly.
> + *
> + * @counter: counter info string to be parsed.
> + * @bitmap: bitmap to set based on counter info parsed.
> + * @fixed: is set to true if the event uses fixed counter.
> + */
> +static int parse_counter(const char *counter,
> + unsigned long *bitmap,
> + bool *fixed)
> +{
> + int ret = 0;
> + char *p;
> + char *tok;
> + int pos = 0;
> +
> + ret = parse_fixed_counter(counter, bitmap, fixed);
> + // ret==0 means matched with fixed counter
> + if (ret == 0)
> + return ret;
> +
> + p = strdup(counter);
> + tok = strtok(p, ",");
> + if (!tok)
> + return -ENOENT;
> +
> + while (tok) {
> + pos = atoi(tok);
> + ret = set_counter_bitmap(pos, bitmap);
> + if (ret)
> + return ret;
> + tok = strtok(NULL, ",");
> + }
> + return 0;
> +}
> +
> +static struct metricgroup__event_info *event_info__new(const char *name,
> + const char *pmu_name,
> + const char *counter,
> + bool free_counter)
> +{
> + int ret = 0;
> + char *bit_buf = malloc(NR_COUNTERS);
> + bool fixed_counter = false;
> + struct metricgroup__event_info *e;
> +
> + e = zalloc(sizeof(*e));
> + if (!e)
> + return NULL;
> + if (!pmu_name)
> + pmu_name = "core";
> +
> + e->name = name;
> + e->free_counter = free_counter;
> + e->pmu_name = strdup(pmu_name);
> + if (free_counter) {
> + ret = set_counter_bitmap(0, e->counters);
> + if (ret)
> + return NULL;
> + } else {
> + ret = parse_counter(counter, e->counters, &fixed_counter);
> + if (ret)
> + return NULL;
> + e->fixed_counter = fixed_counter;
> + }
> +
> + bitmap_scnprintf(e->counters, NR_COUNTERS, bit_buf, NR_COUNTERS);
> + pr_debug("Event %s requires pmu %s counter: %s bitmap %s, [pmu=%s]\n",
> + e->name, e->pmu_name, counter, bit_buf, pmu_name);
> +
> + return e;
> +}
> +
> +struct metricgroup__add_metric_event_data {
> + struct list_head *list;
> + /* pure event name, exclude umask and other info*/
> + const char *event_name;
> + /* event name and umask if applicable*/
> + const char *event_id;
> +};
> +
> +static int metricgroup__add_metric_event_callback(const struct pmu_event *pe,
> + const struct pmu_events_table *table __maybe_unused,
> + void *data)
> +{
> + struct metricgroup__event_info *event;
> + struct metricgroup__add_metric_event_data *d = data;
> +
> + if (!strcasecmp(pe->name, d->event_name)) {
> + event = event_info__new(d->event_id, pe->pmu, pe->counter, /*free_counter=*/false);
> + if (!event)
> + return -ENOMEM;
> + list_add(&event->nd, d->list);
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * get_metricgroup_events - Find counter requirement of events from the
> + * pmu_events table
> + * @full_id: the full event identifiers.
> + * @table: pmu_events table that is searched for event data.
> + * @event_info_list: the list that the new event counter info added to.
> + */
> +static int get_metricgroup_events(const char *full_id,
> + const struct pmu_events_table *table,
> + struct list_head *event_info_list)
> +{
> + LIST_HEAD(list);
> + int ret = 0;
> + const char *id;
> + const char *rsep, *sep = strchr(full_id, '@');
> +
> + if (sep) {
> + rsep = strchr(full_id, ',');
> + id = strndup(sep + 1, rsep - sep - 1);
> + if (ret)
> + goto out;
> + } else {
> + id = full_id;
> + }
> + {
> + struct metricgroup__add_metric_event_data data = {
> + .list = &list,
> + .event_name = id,
> + .event_id = full_id,
> + };
> + ret = pmu_events_table_for_each_event(table,
> + metricgroup__add_metric_event_callback, &data);
> + }
> +
> +out:
> + list_splice(&list, event_info_list);
> + return ret;
> +}
> +
> /**
> * hw_aware_build_grouping - Build event groupings by reading counter
> * requirement of the events and counter available on the system from
> @@ -1445,9 +1621,25 @@ static int hw_aware_build_grouping(struct expr_parse_ctx *ctx __maybe_unused,
> const char *modifier __maybe_unused)
> {
> int ret = 0;
> + struct hashmap_entry *cur;
> + LIST_HEAD(pmu_info_list);
> + LIST_HEAD(event_info_list);
> + size_t bkt;
> + const struct pmu_events_table *etable = perf_pmu__find_events_table(NULL);
> +
> +#define RETURN_IF_NON_ZERO(x) do { if (x) return x; } while (0)
> + hashmap__for_each_entry(ctx->ids, cur, bkt) {
> + const char *id = cur->pkey;
> +
> + pr_debug("found event %s\n", id);
> +
> + ret = get_metricgroup_events(id, etable, &event_info_list);
> + if (ret)
> + return ret;
> + }
>
> - pr_debug("This is a placeholder\n");
> return ret;
> +#undef RETURN_IF_NON_ZERO
> }
>
> static void group_str_free(struct metricgroup__group_strs *g)
> @@ -1521,8 +1713,6 @@ static int hw_aware_parse_ids(struct perf_pmu *fake_pmu,
> *out_evlist = parsed_evlist;
> parsed_evlist = NULL;
> err_out:
> - parse_events_error__exit(&parse_error);
> - evlist__delete(parsed_evlist);
> metricgroup__free_grouping_strs(&groupings);
> return ret;
> }
> diff --git a/tools/perf/util/metricgroup.h b/tools/perf/util/metricgroup.h
> index 89809df85644..3704545c9a11 100644
> --- a/tools/perf/util/metricgroup.h
> +++ b/tools/perf/util/metricgroup.h
> @@ -5,6 +5,7 @@
> #include <linux/list.h>
> #include <linux/rbtree.h>
> #include <stdbool.h>
> +#include <linux/bitmap.h>
> #include "pmu-events/pmu-events.h"
> #include "strbuf.h"
>
> @@ -67,6 +68,32 @@ struct metric_expr {
> int runtime;
> };
>
If this is just used in metricgroup.c then it'd be better to keep the
definitions there for the sake of encapsulation.
> +/* Maximum number of counters per PMU*/
> +#define NR_COUNTERS 16
Fixed and/or generic?
> +/*
> + * Transfer bit position in the bitmap to ensure start assigning counter from
> + * the last GP counter to the first.
> + * bit15 <---> bit0
> + * [GP8-GP15] [GP0-GP7]
> + */
> +#define TRANSFER_FIRST_BYTE(pos) (7 - pos)
> +#define TRANSFER_SEC_BYTE(pos) (23 - pos)
Not sure why this bit flipping is necessary, if fixed counters are
separated out to their own bitmap does it help?
> +
> +/**
> + * An event used in a metric. This info is for metric grouping.
> + */
> +struct metricgroup__event_info {
> + struct list_head nd;
> + /** The name of the event. */
> + const char *name;
> + /** The name of the pmu the event be collected on. */
> + const char *pmu_name;
Could we use the "struct pmu*" here?
> + bool fixed_counter;
> + bool free_counter;
Missing comment for *_counter.
Thanks,
Ian
> + /** The counters the event allowed to be collected on. */
> + DECLARE_BITMAP(counters, NR_COUNTERS);
> +};
> +
> /**
> * Each group is one node in the group string list.
> */
> --
> 2.39.3
>
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