From fa66f07aa1f0950e1dc78b7ab39728b3f8aa77a1 Mon Sep 17 00:00:00 2001 From: Stephane Eranian Date: Thu, 26 Aug 2010 16:40:01 +0200 Subject: perf_events: Fix time tracking for events with pid != -1 and cpu != -1 Per-thread events with a cpu filter, i.e., cpu != -1, were not reporting correct timings when the thread never ran on the monitored cpu. The time enabled was reported as a negative value. This patch fixes the problem by updating tstamp_stopped, tstamp_running in event_sched_out() for events with filters and which are marked as INACTIVE. The function group_sched_out() is modified to systematically call into event_sched_out() to avoid duplicating the timing adjustment code twice. With the patch, I now get: $ task_cpu -i -e unhalted_core_cycles,unhalted_core_cycles noploop 2 noploop for 2 seconds CPU0 0 unhalted_core_cycles (ena=1,991,136,594, run=0) CPU0 0 unhalted_core_cycles (ena=1,991,136,594, run=0) CPU1 0 unhalted_core_cycles (ena=1,991,136,594, run=0) CPU1 0 unhalted_core_cycles (ena=1,991,136,594, run=0) CPU2 0 unhalted_core_cycles (ena=1,991,136,594, run=0) CPU2 0 unhalted_core_cycles (ena=1,991,136,594, run=0) CPU3 4,747,990,931 unhalted_core_cycles (ena=1,991,136,594, run=1,991,136,594) CPU3 4,747,990,931 unhalted_core_cycles (ena=1,991,136,594, run=1,991,136,594) Signed-off-by: Stephane Eranian Acked-by: Peter Zijlstra Cc: paulus@samba.org Cc: davem@davemloft.net Cc: fweisbec@gmail.com Cc: perfmon2-devel@lists.sf.net Cc: eranian@google.com LKML-Reference: <4c76802d.aae9d80a.115d.70fe@mx.google.com> Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 403d1804b198..657555a5f30f 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -402,11 +402,31 @@ static void perf_group_detach(struct perf_event *event) } } +static inline int +event_filter_match(struct perf_event *event) +{ + return event->cpu == -1 || event->cpu == smp_processor_id(); +} + static void event_sched_out(struct perf_event *event, struct perf_cpu_context *cpuctx, struct perf_event_context *ctx) { + u64 delta; + /* + * An event which could not be activated because of + * filter mismatch still needs to have its timings + * maintained, otherwise bogus information is return + * via read() for time_enabled, time_running: + */ + if (event->state == PERF_EVENT_STATE_INACTIVE + && !event_filter_match(event)) { + delta = ctx->time - event->tstamp_stopped; + event->tstamp_running += delta; + event->tstamp_stopped = ctx->time; + } + if (event->state != PERF_EVENT_STATE_ACTIVE) return; @@ -432,9 +452,7 @@ group_sched_out(struct perf_event *group_event, struct perf_event_context *ctx) { struct perf_event *event; - - if (group_event->state != PERF_EVENT_STATE_ACTIVE) - return; + int state = group_event->state; event_sched_out(group_event, cpuctx, ctx); @@ -444,7 +462,7 @@ group_sched_out(struct perf_event *group_event, list_for_each_entry(event, &group_event->sibling_list, group_entry) event_sched_out(event, cpuctx, ctx); - if (group_event->attr.exclusive) + if (state == PERF_EVENT_STATE_ACTIVE && group_event->attr.exclusive) cpuctx->exclusive = 0; } -- cgit v1.2.3 From 3aaba20f26f58843e8f20611e5c0b1c06954310f Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Mon, 23 Aug 2010 16:50:12 +0800 Subject: tracing: Fix a race in function profile While we are reading trace_stat/functionX and someone just disabled function_profile at that time, we can trigger this: divide error: 0000 [#1] PREEMPT SMP ... EIP is at function_stat_show+0x90/0x230 ... This fix just takes the ftrace_profile_lock and checks if rec->counter is 0. If it's 0, we know the profile buffer has been reset. Signed-off-by: Li Zefan Cc: stable@kernel.org LKML-Reference: <4C723644.4040708@cn.fujitsu.com> Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 0d88ce9b9fb8..7cb1f45a1de1 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -381,12 +381,19 @@ static int function_stat_show(struct seq_file *m, void *v) { struct ftrace_profile *rec = v; char str[KSYM_SYMBOL_LEN]; + int ret = 0; #ifdef CONFIG_FUNCTION_GRAPH_TRACER - static DEFINE_MUTEX(mutex); static struct trace_seq s; unsigned long long avg; unsigned long long stddev; #endif + mutex_lock(&ftrace_profile_lock); + + /* we raced with function_profile_reset() */ + if (unlikely(rec->counter == 0)) { + ret = -EBUSY; + goto out; + } kallsyms_lookup(rec->ip, NULL, NULL, NULL, str); seq_printf(m, " %-30.30s %10lu", str, rec->counter); @@ -408,7 +415,6 @@ static int function_stat_show(struct seq_file *m, void *v) do_div(stddev, (rec->counter - 1) * 1000); } - mutex_lock(&mutex); trace_seq_init(&s); trace_print_graph_duration(rec->time, &s); trace_seq_puts(&s, " "); @@ -416,11 +422,12 @@ static int function_stat_show(struct seq_file *m, void *v) trace_seq_puts(&s, " "); trace_print_graph_duration(stddev, &s); trace_print_seq(m, &s); - mutex_unlock(&mutex); #endif seq_putc(m, '\n'); +out: + mutex_unlock(&ftrace_profile_lock); - return 0; + return ret; } static void ftrace_profile_reset(struct ftrace_profile_stat *stat) -- cgit v1.2.3 From 68d3f1d810500e8b975bdf0b20dd83d060076b4b Mon Sep 17 00:00:00 2001 From: Don Zickus Date: Tue, 31 Aug 2010 23:00:07 -0400 Subject: lockup_detector: Sync touch_*_watchdog back to old semantics During my rewrite, the semantics of touch_nmi_watchdog and touch_softlockup_watchdog changed enough to break some drivers (mostly over preemptable regions). These are cases where long delays on one CPU (due to print_delay for example) can cause long delays on other CPUs - so we must 'touch' the nmi_watchdog flag of those other CPUs as well. This change brings those touch_*_watchdog() functions back in line with to how they used to work. Signed-off-by: Don Zickus Acked-by: Cyrill Gorcunov Cc: peterz@infradead.org Cc: fweisbec@gmail.com LKML-Reference: <1283310009-22168-2-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar --- kernel/watchdog.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 0d53c8e853b1..7f9c3c52ecc1 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -122,7 +122,7 @@ static void __touch_watchdog(void) void touch_softlockup_watchdog(void) { - __get_cpu_var(watchdog_touch_ts) = 0; + __raw_get_cpu_var(watchdog_touch_ts) = 0; } EXPORT_SYMBOL(touch_softlockup_watchdog); @@ -142,7 +142,14 @@ void touch_all_softlockup_watchdogs(void) #ifdef CONFIG_HARDLOCKUP_DETECTOR void touch_nmi_watchdog(void) { - __get_cpu_var(watchdog_nmi_touch) = true; + if (watchdog_enabled) { + unsigned cpu; + + for_each_present_cpu(cpu) { + if (per_cpu(watchdog_nmi_touch, cpu) != true) + per_cpu(watchdog_nmi_touch, cpu) = true; + } + } touch_softlockup_watchdog(); } EXPORT_SYMBOL(touch_nmi_watchdog); @@ -433,6 +440,9 @@ static int watchdog_enable(int cpu) wake_up_process(p); } + /* if any cpu succeeds, watchdog is considered enabled for the system */ + watchdog_enabled = 1; + return 0; } @@ -455,9 +465,6 @@ static void watchdog_disable(int cpu) per_cpu(softlockup_watchdog, cpu) = NULL; kthread_stop(p); } - - /* if any cpu succeeds, watchdog is considered enabled for the system */ - watchdog_enabled = 1; } static void watchdog_enable_all_cpus(void) -- cgit v1.2.3