From 9d91a6f7a489eb914c16b82d927f9d81d629c259 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 18 Jun 2009 11:40:28 +0200 Subject: [PATCH] perf_counter tools: Handle lost events Make use of the new ->data_tail mechanism to tell kernel-space about user-space draining the data stream. Emit lost events (and display them) if they happen. Signed-off-by: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo LKML-Reference: Signed-off-by: Ingo Molnar --- tools/perf/builtin-record.c | 20 ++++++++++++++++---- tools/perf/builtin-report.c | 29 ++++++++++++++++++++++++++++- 2 files changed, 44 insertions(+), 5 deletions(-) diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index e1dfef24887f..06fdfb8b4828 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -78,10 +78,10 @@ struct mmap_data { static struct mmap_data mmap_array[MAX_NR_CPUS][MAX_COUNTERS]; -static unsigned int mmap_read_head(struct mmap_data *md) +static unsigned long mmap_read_head(struct mmap_data *md) { struct perf_counter_mmap_page *pc = md->base; - int head; + long head; head = pc->data_head; rmb(); @@ -89,6 +89,17 @@ static unsigned int mmap_read_head(struct mmap_data *md) return head; } +static void mmap_write_tail(struct mmap_data *md, unsigned long tail) +{ + struct perf_counter_mmap_page *pc = md->base; + + /* + * ensure all reads are done before we write the tail out. + */ + /* mb(); */ + pc->data_tail = tail; +} + static void mmap_read(struct mmap_data *md) { unsigned int head = mmap_read_head(md); @@ -109,7 +120,7 @@ static void mmap_read(struct mmap_data *md) * In either case, truncate and restart at head. */ diff = head - old; - if (diff > md->mask / 2 || diff < 0) { + if (diff < 0) { struct timeval iv; unsigned long msecs; @@ -167,6 +178,7 @@ static void mmap_read(struct mmap_data *md) } md->prev = old; + mmap_write_tail(md, old); } static volatile int done = 0; @@ -424,7 +436,7 @@ static void create_counter(int counter, int cpu, pid_t pid) mmap_array[nr_cpu][counter].prev = 0; mmap_array[nr_cpu][counter].mask = mmap_pages*page_size - 1; mmap_array[nr_cpu][counter].base = mmap(NULL, (mmap_pages+1)*page_size, - PROT_READ, MAP_SHARED, fd[nr_cpu][counter], 0); + PROT_READ|PROT_WRITE, MAP_SHARED, fd[nr_cpu][counter], 0); if (mmap_array[nr_cpu][counter].base == MAP_FAILED) { error("failed to mmap with %d (%s)\n", errno, strerror(errno)); exit(-1); diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c index 9a3805f0c9f2..fe66895111b1 100644 --- a/tools/perf/builtin-report.c +++ b/tools/perf/builtin-report.c @@ -83,6 +83,12 @@ struct period_event { __u64 sample_period; }; +struct lost_event { + struct perf_event_header header; + __u64 id; + __u64 lost; +}; + typedef union event_union { struct perf_event_header header; struct ip_event ip; @@ -90,6 +96,7 @@ typedef union event_union { struct comm_event comm; struct fork_event fork; struct period_event period; + struct lost_event lost; } event_t; static LIST_HEAD(dsos); @@ -1068,7 +1075,8 @@ static unsigned long total = 0, total_mmap = 0, total_comm = 0, total_fork = 0, - total_unknown = 0; + total_unknown = 0, + total_lost = 0; static int validate_chain(struct perf_callchain_entry *chain, event_t *event) { @@ -1260,6 +1268,20 @@ process_period_event(event_t *event, unsigned long offset, unsigned long head) return 0; } +static int +process_lost_event(event_t *event, unsigned long offset, unsigned long head) +{ + dprintf("%p [%p]: PERF_EVENT_LOST: id:%Ld: lost:%Ld\n", + (void *)(offset + head), + (void *)(long)(event->header.size), + event->lost.id, + event->lost.lost); + + total_lost += event->lost.lost; + + return 0; +} + static void trace_event(event_t *event) { unsigned char *raw_event = (void *)event; @@ -1316,6 +1338,10 @@ process_event(event_t *event, unsigned long offset, unsigned long head) case PERF_EVENT_PERIOD: return process_period_event(event, offset, head); + + case PERF_EVENT_LOST: + return process_lost_event(event, offset, head); + /* * We dont process them right now but they are fine: */ @@ -1444,6 +1470,7 @@ static int __cmd_report(void) dprintf(" mmap events: %10ld\n", total_mmap); dprintf(" comm events: %10ld\n", total_comm); dprintf(" fork events: %10ld\n", total_fork); + dprintf(" lost events: %10ld\n", total_lost); dprintf(" unknown events: %10ld\n", total_unknown); if (dump_trace) -- GitLab