Commit-ID: 475113d937adfd150eb82b5e2c5507125a68e7af
Gitweb: http://git.kernel.org/tip/475113d937adfd150eb82b5e2c5507125a68e7af
Author: Jiri Olsa <jo...@kernel.org>
AuthorDate: Wed, 28 Dec 2016 14:31:03 +0100
Committer: Ingo Molnar <mi...@kernel.org>
CommitDate: Sat, 14 Jan 2017 11:06:49 +0100
perf/x86/intel: Account interrupts for PEBS errors
It's possible to set up PEBS events to get only errors and not
any data, like on SNB-X (model 45) and IVB-EP (model 62)
via 2 perf commands running simultaneously:
taskset -c 1 ./perf record -c 4 -e branches:pp -j any -C 10
This leads to a soft lock up, because the error path of the
intel_pmu_drain_pebs_nhm() does not account event->hw.interrupt
for error PEBS interrupts, so in case you're getting ONLY
errors you don't have a way to stop the event when it's over
the max_samples_per_tick limit:
NMI watchdog: BUG: soft lockup - CPU#22 stuck for 22s! [perf_fuzzer:5816]
...
RIP: 0010:[<ffffffff81159232>] [<ffffffff81159232>]
smp_call_function_single+0xe2/0x140
...
Call Trace:
? trace_hardirqs_on_caller+0xf5/0x1b0
? perf_cgroup_attach+0x70/0x70
perf_install_in_context+0x199/0x1b0
? ctx_resched+0x90/0x90
SYSC_perf_event_open+0x641/0xf90
SyS_perf_event_open+0x9/0x10
do_syscall_64+0x6c/0x1f0
entry_SYSCALL64_slow_path+0x25/0x25
Add perf_event_account_interrupt() which does the interrupt
and frequency checks and call it from intel_pmu_drain_pebs_nhm()'s
error path.
We keep the pending_kill and pending_wakeup logic only in the
__perf_event_overflow() path, because they make sense only if
there's any data to deliver.
Signed-off-by: Jiri Olsa <jo...@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Alexander Shishkin <alexander.shish...@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <a...@kernel.org>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Stephane Eranian <eran...@google.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Vince Weaver <vi...@deater.net>
Cc: Vince Weaver <vincent.wea...@maine.edu>
Link: http://lkml.kernel.org/r/1482931866-6018-2-git-send-email-jo...@kernel.org
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
arch/x86/events/intel/ds.c | 6 +++++-
include/linux/perf_event.h | 1 +
kernel/events/core.c | 47 ++++++++++++++++++++++++++++++----------------
3 files changed, 37 insertions(+), 17 deletions(-)
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index be20239..9dfeeec 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1389,9 +1389,13 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs
*iregs)
continue;
/* log dropped samples number */
- if (error[bit])
+ if (error[bit]) {
perf_log_lost_samples(event, error[bit]);
+ if (perf_event_account_interrupt(event))
+ x86_pmu_stop(event, 0);
+ }
+
if (counts[bit]) {
__intel_pmu_pebs_event(event, iregs, base,
top, bit, counts[bit]);
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 4741ecd..78ed810 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1259,6 +1259,7 @@ extern void perf_event_disable(struct perf_event *event);
extern void perf_event_disable_local(struct perf_event *event);
extern void perf_event_disable_inatomic(struct perf_event *event);
extern void perf_event_task_tick(void);
+extern int perf_event_account_interrupt(struct perf_event *event);
#else /* !CONFIG_PERF_EVENTS: */
static inline void *
perf_aux_output_begin(struct perf_output_handle *handle,
diff --git a/kernel/events/core.c b/kernel/events/core.c
index cbc5937..110b38a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7060,25 +7060,12 @@ static void perf_log_itrace_start(struct perf_event
*event)
perf_output_end(&handle);
}
-/*
- * Generic event overflow handling, sampling.
- */
-
-static int __perf_event_overflow(struct perf_event *event,
- int throttle, struct perf_sample_data *data,
- struct pt_regs *regs)
+static int
+__perf_event_account_interrupt(struct perf_event *event, int throttle)
{
- int events = atomic_read(&event->event_limit);
struct hw_perf_event *hwc = &event->hw;
- u64 seq;
int ret = 0;
-
- /*
- * Non-sampling counters might still use the PMI to fold short
- * hardware counters, ignore those.
- */
- if (unlikely(!is_sampling_event(event)))
- return 0;
+ u64 seq;
seq = __this_cpu_read(perf_throttled_seq);
if (seq != hwc->interrupts_seq) {
@@ -7106,6 +7093,34 @@ static int __perf_event_overflow(struct perf_event
*event,
perf_adjust_period(event, delta, hwc->last_period,
true);
}
+ return ret;
+}
+
+int perf_event_account_interrupt(struct perf_event *event)
+{
+ return __perf_event_account_interrupt(event, 1);
+}
+
+/*
+ * Generic event overflow handling, sampling.
+ */
+
+static int __perf_event_overflow(struct perf_event *event,
+ int throttle, struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ int events = atomic_read(&event->event_limit);
+ int ret = 0;
+
+ /*
+ * Non-sampling counters might still use the PMI to fold short
+ * hardware counters, ignore those.
+ */
+ if (unlikely(!is_sampling_event(event)))
+ return 0;
+
+ ret = __perf_event_account_interrupt(event, throttle);
+
/*
* XXX event_limit might not quite work as expected on inherited
* events
