perf_counter: change event definition
Currently the definition of an event is slightly ambiguous. We have
wakeup events, for poll() and SIGIO, which are either generated
when a record crosses a page boundary (hw_events.wakeup_events == 0),
or every wakeup_events new records.
Now a record can be either a counter overflow record, or a number of
different things, like the mmap PROT_EXEC region notifications.
Then there is the PERF_COUNTER_IOC_REFRESH event limit, which only
considers counter overflows.
This patch changes then wakeup_events and SIGIO notification to only
consider overflow events. Furthermore it changes the SIGIO notification
to report SIGHUP when the event limit is reached and the counter will
be disabled.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.266679874@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 81220188..0f5a400 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -439,6 +439,7 @@
/* delayed work for NMIs and such */
int pending_wakeup;
+ int pending_kill;
int pending_disable;
struct perf_pending_entry pending;
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index c05e103..8c8eaf0 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1596,7 +1596,11 @@
rcu_read_unlock();
wake_up_all(&counter->waitq);
- kill_fasync(&counter->fasync, SIGIO, POLL_IN);
+
+ if (counter->pending_kill) {
+ kill_fasync(&counter->fasync, SIGIO, counter->pending_kill);
+ counter->pending_kill = 0;
+ }
}
/*
@@ -1727,6 +1731,7 @@
unsigned int head;
int wakeup;
int nmi;
+ int overflow;
};
static inline void __perf_output_wakeup(struct perf_output_handle *handle)
@@ -1741,7 +1746,7 @@
static int perf_output_begin(struct perf_output_handle *handle,
struct perf_counter *counter, unsigned int size,
- int nmi)
+ int nmi, int overflow)
{
struct perf_mmap_data *data;
unsigned int offset, head;
@@ -1751,8 +1756,9 @@
if (!data)
goto out;
- handle->counter = counter;
- handle->nmi = nmi;
+ handle->counter = counter;
+ handle->nmi = nmi;
+ handle->overflow = overflow;
if (!data->nr_pages)
goto fail;
@@ -1816,7 +1822,7 @@
{
int wakeup_events = handle->counter->hw_event.wakeup_events;
- if (wakeup_events) {
+ if (handle->overflow && wakeup_events) {
int events = atomic_inc_return(&handle->data->events);
if (events >= wakeup_events) {
atomic_sub(wakeup_events, &handle->data->events);
@@ -1891,7 +1897,7 @@
header.size += sizeof(u64);
}
- ret = perf_output_begin(&handle, counter, header.size, nmi);
+ ret = perf_output_begin(&handle, counter, header.size, nmi, 1);
if (ret)
return;
@@ -1955,7 +1961,7 @@
{
struct perf_output_handle handle;
int size = mmap_event->event.header.size;
- int ret = perf_output_begin(&handle, counter, size, 0);
+ int ret = perf_output_begin(&handle, counter, size, 0, 0);
if (ret)
return;
@@ -2084,8 +2090,10 @@
int events = atomic_read(&counter->event_limit);
int ret = 0;
+ counter->pending_kill = POLL_IN;
if (events && atomic_dec_and_test(&counter->event_limit)) {
ret = 1;
+ counter->pending_kill = POLL_HUP;
if (nmi) {
counter->pending_disable = 1;
perf_pending_queue(&counter->pending,