diff options
| -rw-r--r-- | tools/perf/util/evlist.c | 47 | ||||
| -rw-r--r-- | tools/perf/util/evlist.h | 6 |
2 files changed, 51 insertions, 2 deletions
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 398dab1a08cc..efddee5a23e9 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -28,6 +28,8 @@ #define FD(e, x, y) (*(int *)xyarray__entry(e->fd, x, y)) #define SID(e, x, y) xyarray__entry(e->sample_id, x, y) +static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx); + void perf_evlist__init(struct perf_evlist *evlist, struct cpu_map *cpus, struct thread_map *threads) { @@ -651,14 +653,36 @@ union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx) return event; } +static bool perf_mmap__empty(struct perf_mmap *md) +{ + return perf_mmap__read_head(md) != md->prev; +} + +static void perf_evlist__mmap_get(struct perf_evlist *evlist, int idx) +{ + ++evlist->mmap[idx].refcnt; +} + +static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx) +{ + BUG_ON(evlist->mmap[idx].refcnt == 0); + + if (--evlist->mmap[idx].refcnt == 0) + __perf_evlist__munmap(evlist, idx); +} + void perf_evlist__mmap_consume(struct perf_evlist *evlist, int idx) { + struct perf_mmap *md = &evlist->mmap[idx]; + if (!evlist->overwrite) { - struct perf_mmap *md = &evlist->mmap[idx]; unsigned int old = md->prev; perf_mmap__write_tail(md, old); } + + if (md->refcnt == 1 && perf_mmap__empty(md)) + perf_evlist__mmap_put(evlist, idx); } static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx) @@ -666,6 +690,7 @@ static void __perf_evlist__munmap(struct perf_evlist *evlist, int idx) if (evlist->mmap[idx].base != NULL) { munmap(evlist->mmap[idx].base, evlist->mmap_len); evlist->mmap[idx].base = NULL; + evlist->mmap[idx].refcnt = 0; } } @@ -699,6 +724,20 @@ struct mmap_params { static int __perf_evlist__mmap(struct perf_evlist *evlist, int idx, struct mmap_params *mp, int fd) { + /* + * The last one will be done at perf_evlist__mmap_consume(), so that we + * make sure we don't prevent tools from consuming every last event in + * the ring buffer. + * + * I.e. we can get the POLLHUP meaning that the fd doesn't exist + * anymore, but the last events for it are still in the ring buffer, + * waiting to be consumed. + * + * Tools can chose to ignore this at their own discretion, but the + * 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, @@ -734,10 +773,14 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx, } else { if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, *output) != 0) return -1; + + perf_evlist__mmap_get(evlist, idx); } - if (perf_evlist__add_pollfd(evlist, fd) < 0) + if (perf_evlist__add_pollfd(evlist, fd) < 0) { + perf_evlist__mmap_put(evlist, idx); return -1; + } if ((evsel->attr.read_format & PERF_FORMAT_ID) && perf_evlist__id_add_fd(evlist, evsel, cpu, thread, fd) < 0) diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h index fc013704d903..bd312b01e876 100644 --- a/tools/perf/util/evlist.h +++ b/tools/perf/util/evlist.h @@ -18,9 +18,15 @@ struct record_opts; #define PERF_EVLIST__HLIST_BITS 8 #define PERF_EVLIST__HLIST_SIZE (1 << PERF_EVLIST__HLIST_BITS) +/** + * struct perf_mmap - perf's ring buffer mmap details + * + * @refcnt - e.g. code using PERF_EVENT_IOC_SET_OUTPUT to share this + */ struct perf_mmap { void *base; int mask; + int refcnt; unsigned int prev; char event_copy[PERF_SAMPLE_MAX_SIZE]; }; |