linux-kernel - Re: [PATCH v5 1/2] perf pmus: Sort pmus by name then suffix

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Message-ID: <ZOi/KDRRrnkvJmkB@kernel.org>
Date:   Fri, 25 Aug 2023 11:48:08 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        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>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        John Garry <john.g.garry@...cle.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/2] perf pmus: Sort pmus by name then suffix

Em Fri, Aug 25, 2023 at 06:52:36AM -0700, Ian Rogers escreveu:
> Sort PMUs by name. If two PMUs have the same name but differ by
> suffix, sort the suffixes numerically. For example, "breakpoint" comes
> before "cpu", "uncore_imc_free_running_0" comes before
> "uncore_imc_free_running_1". Suffixes need to be treated specially as
> otherwise they will be ordered like 0, 1, 10, 11, .., 2, 20, 21, ..,
> etc. Only PMUs starting 'uncore_' are considered to have a potential
> suffix.
> 
> Sorting of PMUs is done so that later patches can skip duplicate
> uncore PMUs that differ only by there suffix.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/perf/util/pmus.c | 48 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 48 insertions(+)
> 
> diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
> index 4dd5912617ff..b1f6a64693fe 100644
> --- a/tools/perf/util/pmus.c
> +++ b/tools/perf/util/pmus.c
> @@ -1,8 +1,10 @@
>  // SPDX-License-Identifier: GPL-2.0
>  #include <linux/list.h>
> +#include <linux/list_sort.h>
>  #include <linux/zalloc.h>
>  #include <subcmd/pager.h>
>  #include <sys/types.h>
> +#include <ctype.h>
>  #include <dirent.h>
>  #include <pthread.h>
>  #include <string.h>
> @@ -33,6 +35,31 @@ static LIST_HEAD(other_pmus);
>  static bool read_sysfs_core_pmus;
>  static bool read_sysfs_all_pmus;
>  
> +static int pmu_name_len_no_suffix(const char *str, unsigned long *num)
> +{
> +	int orig_len, len;
> +
> +	orig_len = len = strlen(str);
> +
> +	/* Non-uncore PMUs have their full length, for example, i915. */
> +	if (strncmp(str, "uncore_", 7))
> +		return len;

I applied the patch, but we have strstarts() for this case, to avoid
having to count the size of the prefix in tools/include/linux/string.h,
that we copied from the kernel sources:

/**
 * strstarts - does @str start with @prefix?
 * @str: string to examine
 * @prefix: prefix to look for.
 */
static inline bool strstarts(const char *str, const char *prefix)
{
        return strncmp(str, prefix, strlen(prefix)) == 0;
}

I'll change it, ok?

- Arnaldo



> +
> +	/*
> +	 * Count trailing digits and '_', if '_{num}' suffix isn't present use
> +	 * the full length.
> +	 */
> +	while (len > 0 && isdigit(str[len - 1]))
> +		len--;
> +
> +	if (len > 0 && len != orig_len && str[len - 1] == '_') {
> +		if (num)
> +			*num = strtoul(&str[len], NULL, 10);
> +		return len - 1;
> +	}
> +	return orig_len;
> +}
> +
>  void perf_pmus__destroy(void)
>  {
>  	struct perf_pmu *pmu, *tmp;
> @@ -122,6 +149,25 @@ static struct perf_pmu *perf_pmu__find2(int dirfd, const char *name)
>  	return perf_pmu__lookup(core_pmu ? &core_pmus : &other_pmus, dirfd, name);
>  }
>  
> +static int pmus_cmp(void *priv __maybe_unused,
> +		    const struct list_head *lhs, const struct list_head *rhs)
> +{
> +	unsigned long lhs_num, rhs_num;
> +	struct perf_pmu *lhs_pmu = container_of(lhs, struct perf_pmu, list);
> +	struct perf_pmu *rhs_pmu = container_of(rhs, struct perf_pmu, list);
> +	const char *lhs_pmu_name = lhs_pmu->name ?: "";
> +	const char *rhs_pmu_name = rhs_pmu->name ?: "";
> +	int lhs_pmu_name_len = pmu_name_len_no_suffix(lhs_pmu_name, &lhs_num);
> +	int rhs_pmu_name_len = pmu_name_len_no_suffix(rhs_pmu_name, &rhs_num);
> +	int ret = strncmp(lhs_pmu_name, rhs_pmu_name,
> +			lhs_pmu_name_len < rhs_pmu_name_len ? lhs_pmu_name_len : rhs_pmu_name_len);
> +
> +	if (lhs_pmu_name_len != rhs_pmu_name_len || ret != 0 || lhs_pmu_name_len == 0)
> +		return ret;
> +
> +	return lhs_num < rhs_num ? -1 : (lhs_num > rhs_num ? 1 : 0);
> +}
> +
>  /* Add all pmus in sysfs to pmu list: */
>  static void pmu_read_sysfs(bool core_only)
>  {
> @@ -156,6 +202,8 @@ static void pmu_read_sysfs(bool core_only)
>  		if (!perf_pmu__create_placeholder_core_pmu(&core_pmus))
>  			pr_err("Failure to set up any core PMUs\n");
>  	}
> +	list_sort(NULL, &core_pmus, pmus_cmp);
> +	list_sort(NULL, &other_pmus, pmus_cmp);
>  	if (!list_empty(&core_pmus)) {
>  		read_sysfs_core_pmus = true;
>  		if (!core_only)
> -- 
> 2.42.0.rc2.253.gd59a3bf2b4-goog
> 

-- 

- Arnaldo