From 04391debc3e1195222a4dbb162ace6542dd89c1c Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Sat, 15 Jan 2011 10:40:59 -0200 Subject: perf evlist: Steal mmap reading routine from 'perf top' Will be used in the upcoming 'perf test' entry for the evlist mmap routines. Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Mike Galbraith Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Tom Zanussi LKML-Reference: Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evlist.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++ tools/perf/util/evlist.h | 4 ++++ 2 files changed, 66 insertions(+) (limited to 'tools/perf/util') diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index deb82a4fc31..4b3b84cd71a 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -95,3 +95,65 @@ struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id) return sid->evsel; return NULL; } + +event_t *perf_evlist__read_on_cpu(struct perf_evlist *evlist, int cpu) +{ + /* XXX Move this to perf.c, making it generally available */ + unsigned int page_size = sysconf(_SC_PAGE_SIZE); + struct perf_mmap *md = &evlist->mmap[cpu]; + unsigned int head = perf_mmap__read_head(md); + unsigned int old = md->prev; + unsigned char *data = md->base + page_size; + event_t *event = NULL; + int diff; + + /* + * If we're further behind than half the buffer, there's a chance + * the writer will bite our tail and mess up the samples under us. + * + * If we somehow ended up ahead of the head, we got messed up. + * + * In either case, truncate and restart at head. + */ + diff = head - old; + if (diff > md->mask / 2 || diff < 0) { + fprintf(stderr, "WARNING: failed to keep up with mmap data.\n"); + + /* + * head points to a known good entry, start there. + */ + old = head; + } + + if (old != head) { + size_t size; + + event = (event_t *)&data[old & md->mask]; + size = event->header.size; + + /* + * Event straddles the mmap boundary -- header should always + * be inside due to u64 alignment of output. + */ + if ((old & md->mask) + size != ((old + size) & md->mask)) { + unsigned int offset = old; + unsigned int len = min(sizeof(*event), size), cpy; + void *dst = &evlist->event_copy; + + do { + cpy = min(md->mask + 1 - (offset & md->mask), len); + memcpy(dst, &data[offset & md->mask], cpy); + offset += cpy; + dst += cpy; + len -= cpy; + } while (len); + + event = &evlist->event_copy; + } + + old += size; + } + + md->prev = old; + return event; +} diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h index dbfcc79bb99..28712063db9 100644 --- a/tools/perf/util/evlist.h +++ b/tools/perf/util/evlist.h @@ -3,6 +3,7 @@ #include #include "../perf.h" +#include "event.h" struct pollfd; @@ -15,6 +16,7 @@ struct perf_evlist { int nr_entries; int nr_fds; int mmap_len; + event_t event_copy; struct perf_mmap *mmap; struct pollfd *pollfd; }; @@ -32,4 +34,6 @@ void perf_evlist__add_pollfd(struct perf_evlist *evlist, int fd); struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id); +event_t *perf_evlist__read_on_cpu(struct perf_evlist *self, int cpu); + #endif /* __PERF_EVLIST_H */ -- cgit v1.2.3-70-g09d2