Re: [PATCH 27/36] libperf: Add perf_evlist__for_each_mmap function

[Arnaldo Carvalho de Melo]

Em Mon, Oct 07, 2019 at 02:53:35PM +0200, Jiri Olsa escreveu:
> Adding perf_evlist__for_each_mmap function and exporting
> it in perf/evlist.h header, so user can iterate through
> 'struct perf_mmap' objects.
> 
> Adding internal perf_mmap__link function to do the actual
> linking.
> 
> Link: http://lkml.kernel.org/n/tip-5h62ytvpxgozhqix2y41cvex@xxxxxxxxxxxxxx
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
>  tools/perf/lib/evlist.c                  | 26 +++++++++++++++++++++++-
>  tools/perf/lib/include/internal/evlist.h |  2 ++
>  tools/perf/lib/include/internal/mmap.h   |  5 +++--
>  tools/perf/lib/include/perf/evlist.h     |  9 ++++++++
>  tools/perf/lib/libperf.map               |  1 +
>  tools/perf/lib/mmap.c                    |  6 ++++--
>  tools/perf/util/evlist.c                 |  4 +++-
>  7 files changed, 47 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/lib/evlist.c b/tools/perf/lib/evlist.c
> index 65045614c938..4e85d9bb92bf 100644
> --- a/tools/perf/lib/evlist.c
> +++ b/tools/perf/lib/evlist.c
> @@ -347,6 +347,8 @@ static struct perf_mmap* perf_evlist__alloc_mmap(struct perf_evlist *evlist, boo
>  		return NULL;
>  
>  	for (i = 0; i < evlist->nr_mmaps; i++) {
> +		struct perf_mmap *prev = i ? &map[i - 1] : NULL;
> +
>  		/*
>  		 * When the perf_mmap() call is made we grab one refcount, plus
>  		 * one extra to let perf_mmap__consume() get the last
> @@ -356,7 +358,7 @@ static struct perf_mmap* perf_evlist__alloc_mmap(struct perf_evlist *evlist, boo
>  		 * Each PERF_EVENT_IOC_SET_OUTPUT points to this mmap and
>  		 * thus does perf_mmap__get() on it.
>  		 */
> -		perf_mmap__init(&map[i], overwrite, NULL);
> +		perf_mmap__init(&map[i], prev, overwrite, NULL);
>  	}
>  
>  	return map;
> @@ -405,6 +407,15 @@ perf_evlist__mmap_cb_mmap(struct perf_mmap *map, struct perf_mmap_param *mp,
>  	return perf_mmap__mmap(map, mp, output, cpu);
>  }
>  
> +static void perf_evlist__set_mmap0(struct perf_evlist *evlist, struct perf_mmap *map,
> +				   bool overwrite)
> +{
> +	if (overwrite)
> +		evlist->mmap_ovw0 = map;
> +	else
> +		evlist->mmap0 = map;
> +}
> +
>  static int
>  mmap_per_evsel(struct perf_evlist *evlist, struct perf_evlist_mmap_ops *ops,
>  	       int idx, struct perf_mmap_param *mp, int cpu_idx,
> @@ -460,6 +471,9 @@ mmap_per_evsel(struct perf_evlist *evlist, struct perf_evlist_mmap_ops *ops,
>  
>  			if (ops->mmap(map, mp, *output, evlist_cpu) < 0)
>  				return -1;
> +
> +			if (!idx)
> +				perf_evlist__set_mmap0(evlist, map, overwrite);
>  		} else {
>  			if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, *output) != 0)
>  				return -1;
> @@ -605,3 +619,13 @@ void perf_evlist__munmap(struct perf_evlist *evlist)
>  	zfree(&evlist->mmap);
>  	zfree(&evlist->mmap_ovw);
>  }
> +
> +struct perf_mmap*
> +perf_evlist__next_mmap(struct perf_evlist *evlist, struct perf_mmap *map,
> +		       bool overwrite)
> +{
> +	if (map)
> +		return map->next;
> +
> +	return overwrite ? evlist->mmap_ovw0 : evlist->mmap0;
> +}
> diff --git a/tools/perf/lib/include/internal/evlist.h b/tools/perf/lib/include/internal/evlist.h
> index be0b25a70730..513a85cb7bfe 100644
> --- a/tools/perf/lib/include/internal/evlist.h
> +++ b/tools/perf/lib/include/internal/evlist.h
> @@ -25,6 +25,8 @@ struct perf_evlist {
>  	struct hlist_head	 heads[PERF_EVLIST__HLIST_SIZE];
>  	struct perf_mmap	*mmap;
>  	struct perf_mmap	*mmap_ovw;
> +	struct perf_mmap	*mmap0;
> +	struct perf_mmap	*mmap_ovw0;

Why do you use this funny name? Using this "0" suffix? Please pick
something more informative and add a comment on the struct perf_evlist
definiton.

I've processed up to the previous patch, pushed to acme/tmp.perf/core.

- Arnaldo

>  };
>  
>  typedef void
> diff --git a/tools/perf/lib/include/internal/mmap.h b/tools/perf/lib/include/internal/mmap.h
> index b328332b6ccf..f5b4f902b453 100644
> --- a/tools/perf/lib/include/internal/mmap.h
> +++ b/tools/perf/lib/include/internal/mmap.h
> @@ -33,6 +33,7 @@ struct perf_mmap {
>  	u64			 flush;
>  	libperf_unmap_cb_t	 unmap_cb;
>  	char			 event_copy[PERF_SAMPLE_MAX_SIZE] __aligned(8);
> +	struct perf_mmap	*next;
>  };
>  
>  struct perf_mmap_param {
> @@ -42,8 +43,8 @@ struct perf_mmap_param {
>  
>  size_t perf_mmap__mmap_len(struct perf_mmap *map);
>  
> -void perf_mmap__init(struct perf_mmap *map, bool overwrite,
> -		     libperf_unmap_cb_t unmap_cb);
> +void perf_mmap__init(struct perf_mmap *map, struct perf_mmap *prev,
> +		     bool overwrite, libperf_unmap_cb_t unmap_cb);
>  int perf_mmap__mmap(struct perf_mmap *map, struct perf_mmap_param *mp,
>  		    int fd, int cpu);
>  void perf_mmap__munmap(struct perf_mmap *map);
> diff --git a/tools/perf/lib/include/perf/evlist.h b/tools/perf/lib/include/perf/evlist.h
> index 16f526e74d13..8c4b3c28535e 100644
> --- a/tools/perf/lib/include/perf/evlist.h
> +++ b/tools/perf/lib/include/perf/evlist.h
> @@ -3,6 +3,7 @@
>  #define __LIBPERF_EVLIST_H
>  
>  #include <perf/core.h>
> +#include <stdbool.h>
>  
>  struct perf_evlist;
>  struct perf_evsel;
> @@ -38,4 +39,12 @@ LIBPERF_API int perf_evlist__filter_pollfd(struct perf_evlist *evlist,
>  LIBPERF_API int perf_evlist__mmap(struct perf_evlist *evlist, int pages);
>  LIBPERF_API void perf_evlist__munmap(struct perf_evlist *evlist);
>  
> +LIBPERF_API struct perf_mmap *perf_evlist__next_mmap(struct perf_evlist *evlist,
> +						     struct perf_mmap *map,
> +						     bool overwrite);
> +#define perf_evlist__for_each_mmap(evlist, pos, overwrite)		\
> +	for ((pos) = perf_evlist__next_mmap((evlist), NULL, overwrite);	\
> +	     (pos) != NULL;						\
> +	     (pos) = perf_evlist__next_mmap((evlist), (pos), overwrite))
> +
>  #endif /* __LIBPERF_EVLIST_H */
> diff --git a/tools/perf/lib/libperf.map b/tools/perf/lib/libperf.map
> index 2184aba36c3f..8be02afc324b 100644
> --- a/tools/perf/lib/libperf.map
> +++ b/tools/perf/lib/libperf.map
> @@ -43,6 +43,7 @@ LIBPERF_0.0.1 {
>  		perf_evlist__mmap;
>  		perf_evlist__munmap;
>  		perf_evlist__filter_pollfd;
> +		perf_evlist__next_mmap;
>  		perf_mmap__consume;
>  		perf_mmap__read_init;
>  		perf_mmap__read_done;
> diff --git a/tools/perf/lib/mmap.c b/tools/perf/lib/mmap.c
> index fe9e1b095fd7..fe7e9ef8a68c 100644
> --- a/tools/perf/lib/mmap.c
> +++ b/tools/perf/lib/mmap.c
> @@ -12,13 +12,15 @@
>  #include <internal/lib.h>
>  #include "internal.h"
>  
> -void perf_mmap__init(struct perf_mmap *map, bool overwrite,
> -		     libperf_unmap_cb_t unmap_cb)
> +void perf_mmap__init(struct perf_mmap *map, struct perf_mmap *prev,
> +		     bool overwrite, libperf_unmap_cb_t unmap_cb)
>  {
>  	map->fd = -1;
>  	map->overwrite = overwrite;
>  	map->unmap_cb  = unmap_cb;
>  	refcount_set(&map->refcnt, 0);
> +	if (prev)
> +		prev->next = map;
>  }
>  
>  size_t perf_mmap__mmap_len(struct perf_mmap *map)
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 4910ae711b13..469a5476ef1a 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -582,6 +582,8 @@ static struct mmap *evlist__alloc_mmap(struct evlist *evlist,
>  		return NULL;
>  
>  	for (i = 0; i < evlist->core.nr_mmaps; i++) {
> +		struct perf_mmap *prev = i ? &map[i - 1].core : NULL;
> +
>  		/*
>  		 * When the perf_mmap() call is made we grab one refcount, plus
>  		 * one extra to let perf_mmap__consume() get the last
> @@ -591,7 +593,7 @@ static struct mmap *evlist__alloc_mmap(struct evlist *evlist,
>  		 * Each PERF_EVENT_IOC_SET_OUTPUT points to this mmap and
>  		 * thus does perf_mmap__get() on it.
>  		 */
> -		perf_mmap__init(&map[i].core, overwrite, perf_mmap__unmap_cb);
> +		perf_mmap__init(&map[i].core, prev, overwrite, perf_mmap__unmap_cb);
>  	}
>  
>  	return map;
> -- 
> 2.21.0

-- 

- Arnaldo