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SubjectRe: [PATCH 05/37] perf tools: Create separate mmap for dummy tracking event
On 24/12/14 09:15, Namhyung Kim wrote:
> When multi file support is enabled, a dummy tracking event will be
> used to track metadata (like task, comm and mmap events) for a session
> and actual samples will be recorded in separate files.
>
> Provide separate mmap to the dummy tracking event. The size is fixed
> to 128KiB (+ 1 page) as the event rate will be lower than samples. I
> originally wanted to use a single mmap for this but cross-cpu sharing
> is prohibited so it's per-cpu (or per-task) like normal mmaps.
>
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
> tools/perf/builtin-record.c | 9 +++-
> tools/perf/util/evlist.c | 104 +++++++++++++++++++++++++++++++++++---------
> tools/perf/util/evlist.h | 11 ++++-
> 3 files changed, 102 insertions(+), 22 deletions(-)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 054c6e57d3b9..129fab35fdc5 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -69,7 +69,7 @@ static int process_synthesized_event(struct perf_tool *tool,
>
> static int record__mmap_read(struct record *rec, int idx)
> {
> - struct perf_mmap *md = &rec->evlist->mmap[idx];
> + struct perf_mmap *md = perf_evlist__mmap_desc(rec->evlist, idx);
> unsigned int head = perf_mmap__read_head(md);
> unsigned int old = md->prev;
> unsigned char *data = md->base + page_size;
> @@ -105,6 +105,7 @@ static int record__mmap_read(struct record *rec, int idx)
> }
>
> md->prev = old;
> +
> perf_evlist__mmap_consume(rec->evlist, idx);
> out:
> return rc;
> @@ -263,6 +264,12 @@ static int record__mmap_read_all(struct record *rec)
> goto out;
> }
> }
> + if (rec->evlist->track_mmap) {
> + if (record__mmap_read(rec, track_mmap_idx(i)) != 0) {
> + rc = -1;
> + goto out;
> + }
> + }
> }
>
> /*
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 72dff295237e..d99343b988fe 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -27,6 +27,7 @@
>
> static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx);
> static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx);
> +static void __perf_evlist__munmap_track(struct perf_evlist *evlist, int idx);
>
> #define FD(e, x, y) (*(int *)xyarray__entry(e->fd, x, y))
> #define SID(e, x, y) xyarray__entry(e->sample_id, x, y)
> @@ -735,22 +736,39 @@ static bool perf_mmap__empty(struct perf_mmap *md)
> return perf_mmap__read_head(md) != md->prev;
> }
>
> +struct perf_mmap *perf_evlist__mmap_desc(struct perf_evlist *evlist, int idx)
> +{
> + if (idx >= 0)
> + return &evlist->mmap[idx];
> + else
> + return &evlist->track_mmap[track_mmap_idx(idx)];
> +}
> +
> static void perf_evlist__mmap_get(struct perf_evlist *evlist, int idx)
> {
> - ++evlist->mmap[idx].refcnt;
> + struct perf_mmap *md = perf_evlist__mmap_desc(evlist, idx);
> +
> + ++md->refcnt;
> }
>
> static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx)
> {
> - BUG_ON(evlist->mmap[idx].refcnt == 0);
> + struct perf_mmap *md = perf_evlist__mmap_desc(evlist, idx);
> +
> + BUG_ON(md->refcnt == 0);
> +
> + if (--md->refcnt != 0)
> + return;
>
> - if (--evlist->mmap[idx].refcnt == 0)
> + if (idx >= 0)
> __perf_evlist__munmap(evlist, idx);
> + else
> + __perf_evlist__munmap_track(evlist, track_mmap_idx(idx));
> }
>
> void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx)
> {
> - struct perf_mmap *md = &evlist->mmap[idx];
> + struct perf_mmap *md = perf_evlist__mmap_desc(evlist, idx);
>
> if (!evlist->overwrite) {
> unsigned int old = md->prev;
> @@ -771,6 +789,15 @@ static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx)
> }
> }
>
> +static void __perf_evlist__munmap_track(struct perf_evlist *evlist, int idx)
> +{
> + if (evlist->track_mmap[idx].base != NULL) {
> + munmap(evlist->track_mmap[idx].base, TRACK_MMAP_SIZE);
> + evlist->track_mmap[idx].base = NULL;
> + evlist->track_mmap[idx].refcnt = 0;
> + }
> +}
> +
> void perf_evlist__munmap(struct perf_evlist *evlist)
> {
> int i;
> @@ -782,23 +809,43 @@ void perf_evlist__munmap(struct perf_evlist *evlist)
> __perf_evlist__munmap(evlist, i);
>
> zfree(&evlist->mmap);
> +
> + if (evlist->track_mmap == NULL)
> + return;
> +
> + for (i = 0; i < evlist->nr_mmaps; i++)
> + __perf_evlist__munmap_track(evlist, i);
> +
> + zfree(&evlist->track_mmap);
> }
>
> -static int perf_evlist__alloc_mmap(struct perf_evlist *evlist)
> +static int perf_evlist__alloc_mmap(struct perf_evlist *evlist, bool track_mmap)
> {
> evlist->nr_mmaps = cpu_map__nr(evlist->cpus);
> if (cpu_map__empty(evlist->cpus))
> evlist->nr_mmaps = thread_map__nr(evlist->threads);
> evlist->mmap = zalloc(evlist->nr_mmaps * sizeof(struct perf_mmap));
> - return evlist->mmap != NULL ? 0 : -ENOMEM;
> + if (evlist->mmap == NULL)
> + return -ENOMEM;
> +
> + if (track_mmap) {
> + evlist->track_mmap = calloc(evlist->nr_mmaps,
> + sizeof(struct perf_mmap));
> + if (evlist->track_mmap == NULL) {
> + zfree(&evlist->mmap);
> + return -ENOMEM;
> + }
> + }
> + return 0;
> }
>
> struct mmap_params {
> - int prot;
> - int mask;
> + int prot;
> + size_t len;
> };
>
> -static int __perf_evlist__mmap(struct perf_evlist *evlist, int idx,
> +static int __perf_evlist__mmap(struct perf_evlist *evlist __maybe_unused,
> + struct perf_mmap *pmmap,
> struct mmap_params *mp, int fd)
> {
> /*
> @@ -814,15 +861,14 @@ static int __perf_evlist__mmap(struct perf_evlist *evlist, int idx,
> * evlist layer can't just drop it when filtering events in
> * perf_evlist__filter_pollfd().
> */
> - evlist->mmap[idx].refcnt = 2;
> - evlist->mmap[idx].prev = 0;
> - evlist->mmap[idx].mask = mp->mask;
> - evlist->mmap[idx].base = mmap(NULL, evlist->mmap_len, mp->prot,
> - MAP_SHARED, fd, 0);
> - if (evlist->mmap[idx].base == MAP_FAILED) {
> + pmmap->refcnt = 2;
> + pmmap->prev = 0;
> + pmmap->mask = mp->len - page_size - 1;
> + pmmap->base = mmap(NULL, mp->len, mp->prot, MAP_SHARED, fd, 0);
> + if (pmmap->base == MAP_FAILED) {
> pr_debug2("failed to mmap perf event ring buffer, error %d\n",
> errno);
> - evlist->mmap[idx].base = NULL;
> + pmmap->base = NULL;
> return -1;
> }
>
> @@ -843,9 +889,22 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
>
> fd = FD(evsel, cpu, thread);
>
> - if (*output == -1) {
> + if (perf_evsel__is_dummy_tracking(evsel)) {
> + struct mmap_params track_mp = {
> + .prot = mp->prot,
> + .len = TRACK_MMAP_SIZE,
> + };
> +
> + if (__perf_evlist__mmap(evlist, &evlist->track_mmap[idx],
> + &track_mp, fd) < 0)
> + return -1;
> +
> + /* mark idx as track mmap idx (negative) */
> + idx = track_mmap_idx(idx);

Do you not still need to do SET_OUTPUT when there are multiple cpus and
multiple pids?


> + } else if (*output == -1) {
> *output = fd;
> - if (__perf_evlist__mmap(evlist, idx, mp, *output) < 0)
> + if (__perf_evlist__mmap(evlist, &evlist->mmap[idx],
> + mp, *output) < 0)
> return -1;
> } else {
> if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, *output) != 0)
> @@ -874,6 +933,11 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
> perf_evlist__set_sid_idx(evlist, evsel, idx, cpu,
> thread);
> }
> +
> + if (mp->track && perf_evsel__is_dummy_tracking(evsel)) {
> + /* restore idx as normal idx (positive) */
> + idx = track_mmap_idx(idx);
> + }
> }
>
> return 0;
> @@ -1025,7 +1089,7 @@ int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
> .prot = PROT_READ | (overwrite ? 0 : PROT_WRITE),
> };
>
> - if (evlist->mmap == NULL && perf_evlist__alloc_mmap(evlist) < 0)
> + if (evlist->mmap == NULL && perf_evlist__alloc_mmap(evlist, use_track_mmap) < 0)
> return -ENOMEM;
>
> if (evlist->pollfd.entries == NULL && perf_evlist__alloc_pollfd(evlist) < 0)
> @@ -1034,7 +1098,7 @@ int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
> evlist->overwrite = overwrite;
> evlist->mmap_len = perf_evlist__mmap_size(pages);
> pr_debug("mmap size %zuB\n", evlist->mmap_len);
> - mp.mask = evlist->mmap_len - page_size - 1;
> + mp.len = evlist->mmap_len;
>
> evlist__for_each(evlist, evsel) {
> if ((evsel->attr.read_format & PERF_FORMAT_ID) &&
> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
> index b974bddf6b8b..b7f54b8577f7 100644
> --- a/tools/perf/util/evlist.h
> +++ b/tools/perf/util/evlist.h
> @@ -48,11 +48,14 @@ struct perf_evlist {
> bool overwrite;
> struct fdarray pollfd;
> struct perf_mmap *mmap;
> + struct perf_mmap *track_mmap;
> struct thread_map *threads;
> struct cpu_map *cpus;
> struct perf_evsel *selected;
> };
>
> +#define TRACK_MMAP_SIZE (((128 * 1024 / page_size) + 1) * page_size)
> +
> struct perf_evsel_str_handler {
> const char *name;
> void *handler;
> @@ -100,8 +103,8 @@ struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id);
> struct perf_sample_id *perf_evlist__id2sid(struct perf_evlist *evlist, u64 id);
>
> union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx);
> -
> void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx);
> +struct perf_mmap *perf_evlist__mmap_desc(struct perf_evlist *evlist, int idx);
>
> int perf_evlist__open(struct perf_evlist *evlist);
> void perf_evlist__close(struct perf_evlist *evlist);
> @@ -211,6 +214,12 @@ bool perf_evlist__can_select_event(struct perf_evlist *evlist, const char *str);
> void perf_evlist__to_front(struct perf_evlist *evlist,
> struct perf_evsel *move_evsel);
>
> +/* convert from/to negative idx for track mmaps */
> +static inline int track_mmap_idx(int idx)
> +{
> + return -idx - 1;
> +}
> +
> /**
> * __evlist__for_each - iterate thru all the evsels
> * @list: list_head instance to iterate
>



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