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Date:   Fri, 20 Jan 2023 14:43:44 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     James Clark <james.clark@arm.com>
Cc:     linux-perf-users@vger.kernel.org, tanmay@marvell.com,
        leo.yan@linaro.org, mike.leach@linaro.org, sgoutham@marvell.com,
        gcherian@marvell.com, lcherian@marvell.com, bbhushan2@marvell.com,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        John Garry <john.g.garry@oracle.com>,
        Will Deacon <will@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>, coresight@lists.linaro.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 2/8] perf: Use perf_pmu__open_file() and
 perf_pmu__scan_file()
Message-ID: <Y8rS0BOUeXaGvwPv@kernel.org>
References: <20230120143702.4035046-1-james.clark@arm.com>
 <20230120143702.4035046-3-james.clark@arm.com>
 <Y8rNtO5HNcPJDpQ2@kernel.org>
 <Y8rQLirdlgU8nMEW@kernel.org>
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In-Reply-To: <Y8rQLirdlgU8nMEW@kernel.org>
Precedence: bulk

Em Fri, Jan 20, 2023 at 02:32:30PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Fri, Jan 20, 2023 at 02:21:56PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Fri, Jan 20, 2023 at 02:36:55PM +0000, James Clark escreveu:
> > > Remove some code that duplicates existing methods. Copy strings where
> > > const strings are required.
> > > 
> > > No functional changes.
> > 
> > 
> > Have you used 'perf test'?
> > 
> > [acme@quaco perf]$ perf test -v python
> > Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc
> >  19: 'import perf' in python                                         :
> > --- start ---
> > test child forked, pid 232379
> > python usage test: "echo "import sys ; sys.path.append('/tmp/build/perf/python'); import perf" | '/usr/bin/python3' "
> > Traceback (most recent call last):
> >   File "<stdin>", line 1, in <module>
> > ImportError: /tmp/build/perf/python/perf.cpython-310-x86_64-linux-gnu.so: undefined symbol: perf_pmu__scan_file
> > test child finished with -1
> > ---- end ----
> > 'import perf' in python: FAILED!
> > [acme@quaco perf]$
> 
> I added this to this cset, now it passes.

So, what I have is now at my tmp.perf/core branch, pending container
testing, later today probably will move to perf/core, so that it gets
exposure on linux-next for v6.3.

For your convenience:

https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/log/?h=tmp.perf/core

Thanks,

- Arnaldo
 
> diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
> index d948455e5ed43656..9e5d881b098767a3 100644
> --- a/tools/perf/util/python.c
> +++ b/tools/perf/util/python.c
> @@ -20,6 +20,7 @@
>  #include "stat.h"
>  #include "metricgroup.h"
>  #include "util/env.h"
> +#include "util/pmu.h"
>  #include <internal/lib.h>
>  #include "util.h"
>  
> @@ -83,7 +84,7 @@ void perf_stat__collect_metric_expr(struct evlist *evsel_list)
>  }
>  
>  /*
> - * This one is needed not to drag the PMU bandwagon, jevents generated
> + * These ones are needed not to drag the PMU bandwagon, jevents generated
>   * pmu_sys_event_tables, etc and evsel__find_pmu() is used so far just for
>   * doing per PMU perf_event_attr.exclude_guest handling, not really needed, so
>   * far, for the perf python binding known usecases, revisit if this become
> @@ -94,6 +95,11 @@ struct perf_pmu *evsel__find_pmu(struct evsel *evsel __maybe_unused)
>  	return NULL;
>  }
>  
> +int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt, ...)
> +{
> +	return EOF;
> +}
> +
>  /*
>   * Add this one here not to drag util/metricgroup.c
>   */
>   
> > > Reviewed-by: Leo Yan <leo.yan@linaro.org>
> > > Signed-off-by: James Clark <james.clark@arm.com>
> > > ---
> > >  tools/perf/util/cputopo.c    |  9 +-------
> > >  tools/perf/util/pmu-hybrid.c | 27 +++++-------------------
> > >  tools/perf/util/pmu.c        | 40 +++++++++++-------------------------
> > >  tools/perf/util/pmu.h        |  3 ++-
> > >  4 files changed, 20 insertions(+), 59 deletions(-)
> > > 
> > > diff --git a/tools/perf/util/cputopo.c b/tools/perf/util/cputopo.c
> > > index 1a3ff6449158..e08797c3cdbc 100644
> > > --- a/tools/perf/util/cputopo.c
> > > +++ b/tools/perf/util/cputopo.c
> > > @@ -422,8 +422,6 @@ void numa_topology__delete(struct numa_topology *tp)
> > >  static int load_hybrid_node(struct hybrid_topology_node *node,
> > >  			    struct perf_pmu *pmu)
> > >  {
> > > -	const char *sysfs;
> > > -	char path[PATH_MAX];
> > >  	char *buf = NULL, *p;
> > >  	FILE *fp;
> > >  	size_t len = 0;
> > > @@ -432,12 +430,7 @@ static int load_hybrid_node(struct hybrid_topology_node *node,
> > >  	if (!node->pmu_name)
> > >  		return -1;
> > >  
> > > -	sysfs = sysfs__mountpoint();
> > > -	if (!sysfs)
> > > -		goto err;
> > > -
> > > -	snprintf(path, PATH_MAX, CPUS_TEMPLATE_CPU, sysfs, pmu->name);
> > > -	fp = fopen(path, "r");
> > > +	fp = perf_pmu__open_file(pmu, "cpus");
> > >  	if (!fp)
> > >  		goto err;
> > >  
> > > diff --git a/tools/perf/util/pmu-hybrid.c b/tools/perf/util/pmu-hybrid.c
> > > index f51ccaac60ee..38628805a952 100644
> > > --- a/tools/perf/util/pmu-hybrid.c
> > > +++ b/tools/perf/util/pmu-hybrid.c
> > > @@ -20,32 +20,15 @@ LIST_HEAD(perf_pmu__hybrid_pmus);
> > >  
> > >  bool perf_pmu__hybrid_mounted(const char *name)
> > >  {
> > > -	char path[PATH_MAX];
> > > -	const char *sysfs;
> > > -	FILE *file;
> > > -	int n, cpu;
> > > +	int cpu;
> > > +	char pmu_name[PATH_MAX];
> > > +	struct perf_pmu pmu = {.name = pmu_name};
> > >  
> > >  	if (strncmp(name, "cpu_", 4))
> > >  		return false;
> > >  
> > > -	sysfs = sysfs__mountpoint();
> > > -	if (!sysfs)
> > > -		return false;
> > > -
> > > -	snprintf(path, PATH_MAX, CPUS_TEMPLATE_CPU, sysfs, name);
> > > -	if (!file_available(path))
> > > -		return false;
> > > -
> > > -	file = fopen(path, "r");
> > > -	if (!file)
> > > -		return false;
> > > -
> > > -	n = fscanf(file, "%u", &cpu);
> > > -	fclose(file);
> > > -	if (n <= 0)
> > > -		return false;
> > > -
> > > -	return true;
> > > +	strlcpy(pmu_name, name, sizeof(pmu_name));
> > > +	return perf_pmu__scan_file(&pmu, "cpus", "%u", &cpu) > 0;
> > >  }
> > >  
> > >  struct perf_pmu *perf_pmu__find_hybrid_pmu(const char *name)
> > > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> > > index 1edbb714ff32..a771a5972fc5 100644
> > > --- a/tools/perf/util/pmu.c
> > > +++ b/tools/perf/util/pmu.c
> > > @@ -571,45 +571,31 @@ static void pmu_read_sysfs(void)
> > >  	closedir(dir);
> > >  }
> > >  
> > > -static struct perf_cpu_map *__pmu_cpumask(const char *path)
> > > -{
> > > -	FILE *file;
> > > -	struct perf_cpu_map *cpus;
> > > -
> > > -	file = fopen(path, "r");
> > > -	if (!file)
> > > -		return NULL;
> > > -
> > > -	cpus = perf_cpu_map__read(file);
> > > -	fclose(file);
> > > -	return cpus;
> > > -}
> > > -
> > >  /*
> > >   * Uncore PMUs have a "cpumask" file under sysfs. CPU PMUs (e.g. on arm/arm64)
> > >   * may have a "cpus" file.
> > >   */
> > >  #define SYS_TEMPLATE_ID	"./bus/event_source/devices/%s/identifier"
> > > -#define CPUS_TEMPLATE_UNCORE	"%s/bus/event_source/devices/%s/cpumask"
> > >  
> > >  static struct perf_cpu_map *pmu_cpumask(const char *name)
> > >  {
> > > -	char path[PATH_MAX];
> > >  	struct perf_cpu_map *cpus;
> > > -	const char *sysfs = sysfs__mountpoint();
> > >  	const char *templates[] = {
> > > -		CPUS_TEMPLATE_UNCORE,
> > > -		CPUS_TEMPLATE_CPU,
> > > +		"cpumask",
> > > +		"cpus",
> > >  		NULL
> > >  	};
> > >  	const char **template;
> > > +	char pmu_name[PATH_MAX];
> > > +	struct perf_pmu pmu = {.name = pmu_name};
> > > +	FILE *file;
> > >  
> > > -	if (!sysfs)
> > > -		return NULL;
> > > -
> > > +	strlcpy(pmu_name, name, sizeof(pmu_name));
> > >  	for (template = templates; *template; template++) {
> > > -		snprintf(path, PATH_MAX, *template, sysfs, name);
> > > -		cpus = __pmu_cpumask(path);
> > > +		file = perf_pmu__open_file(&pmu, *template);
> > > +		if (!file)
> > > +			continue;
> > > +		cpus = perf_cpu_map__read(file);
> > >  		if (cpus)
> > >  			return cpus;
> > >  	}
> > > @@ -620,13 +606,11 @@ static struct perf_cpu_map *pmu_cpumask(const char *name)
> > >  static bool pmu_is_uncore(const char *name)
> > >  {
> > >  	char path[PATH_MAX];
> > > -	const char *sysfs;
> > >  
> > >  	if (perf_pmu__hybrid_mounted(name))
> > >  		return false;
> > >  
> > > -	sysfs = sysfs__mountpoint();
> > > -	snprintf(path, PATH_MAX, CPUS_TEMPLATE_UNCORE, sysfs, name);
> > > +	perf_pmu__pathname_scnprintf(path, sizeof(path), name, "cpumask");
> > >  	return file_available(path);
> > >  }
> > >  
> > > @@ -1737,7 +1721,7 @@ bool pmu_have_event(const char *pname, const char *name)
> > >  	return false;
> > >  }
> > >  
> > > -static FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name)
> > > +FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name)
> > >  {
> > >  	char path[PATH_MAX];
> > >  
> > > diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> > > index 96d030c8b3b3..742d4db319a0 100644
> > > --- a/tools/perf/util/pmu.h
> > > +++ b/tools/perf/util/pmu.h
> > > @@ -7,6 +7,7 @@
> > >  #include <linux/perf_event.h>
> > >  #include <linux/list.h>
> > >  #include <stdbool.h>
> > > +#include <stdio.h>
> > >  #include "parse-events.h"
> > >  #include "pmu-events/pmu-events.h"
> > >  
> > > @@ -22,7 +23,6 @@ enum {
> > >  };
> > >  
> > >  #define PERF_PMU_FORMAT_BITS 64
> > > -#define CPUS_TEMPLATE_CPU	"%s/bus/event_source/devices/%s/cpus"
> > >  #define MAX_PMU_NAME_LEN 128
> > >  
> > >  struct perf_event_attr;
> > > @@ -262,5 +262,6 @@ double perf_pmu__cpu_slots_per_cycle(void);
> > >  int perf_pmu__event_source_devices_scnprintf(char *pathname, size_t size);
> > >  int perf_pmu__pathname_scnprintf(char *buf, size_t size,
> > >  				 const char *pmu_name, const char *filename);
> > > +FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name);
> > >  
> > >  #endif /* __PMU_H */
> > > -- 
> > > 2.25.1
> > > 
> > 
> > -- 
> > 
> > - Arnaldo
> 
> -- 
> 
> - Arnaldo

-- 

- Arnaldo