On 10/24/2011 06:56 PM, Deng-Cheng Zhu wrote:
When arch level event init is called, the event is not yet connected to
the PMU, thereby causing validate_group() to always do dummy work. On MIPS,
this is due to the following lines in validate_event() called by
validate_group():
if (event->pmu !=&pmu || event->state<= PERF_EVENT_STATE_OFF)
return 1;
This patch fixes it.
Signed-off-by: Deng-Cheng Zhu<dczhu@xxxxxxxx>
Cc: Peter Zijlstra<a.p.zijlstra@xxxxxxxxx>
Cc: Paul Mackerras<paulus@xxxxxxxxx>
Cc: Ingo Molnar<mingo@xxxxxxx>
Cc: Arnaldo Carvalho de Melo<acme@xxxxxxxxxxxxxxxxxx>
Cc: David Daney<david.daney@xxxxxxxxxx>
---
arch/mips/kernel/perf_event_mipsxx.c | 17 +++++++++++++----
1 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/arch/mips/kernel/perf_event_mipsxx.c b/arch/mips/kernel/perf_event_mipsxx.c
index 1f654ca..c804fdd 100644
--- a/arch/mips/kernel/perf_event_mipsxx.c
+++ b/arch/mips/kernel/perf_event_mipsxx.c
@@ -548,6 +548,7 @@ static int __hw_perf_event_init(struct perf_event *event)
struct perf_event_attr *attr =&event->attr;
struct hw_perf_event *hwc =&event->hw;
const struct mips_perf_event *pev;
+ struct pmu *tmp;
int err;
/* Returning MIPS event descriptor for generic perf event. */
@@ -611,11 +612,19 @@ static int __hw_perf_event_init(struct perf_event *event)
}
err = 0;
- if (event->group_leader != event) {
+
+ /*
+ * we temporarily connect event to its pmu such that
+ * validate_event() in validate_group() can classify
+ * it as a MIPS event by passing (event->pmu ==&pmu).
+ */
+ tmp = event->pmu;
+ event->pmu =&pmu;
+
+ if (event->group_leader != event)
err = validate_group(event);
- if (err)
- return -EINVAL;
- }
+
+ event->pmu = tmp;
event->destroy = hw_perf_event_destroy;
After looking at David Ahern's reply to my another patch (link
provided below), I started to think whether the PMU and event state
checks are redundant in validate_event() on MIPS (ARM may also have
the same consideration).
The related patch link:
http://www.spinics.net/lists/kernel/msg1252452.html
_If_ the state fix goes to group checks instead of to the perf tool,
then the following line in validate_event() on MIPS seems redundant:
if (event->pmu !=&pmu || event->state <= PERF_EVENT_STATE_OFF)
return 1;
This is because validate_event() is only called by validate_group()
which is called only by __hw_perf_event_init(), and the issue of the
pmu check is already addressed in this patch, and we don't want the
grouped events which are in PERF_EVENT_STATE_OFF (by "attr->disabled =
1") to be filtered out here.
Also, _if_ the state fix goes to group checks instead of to the perf
tool, then X86 may need a patch to allow collect_events() to do real
work in validate_group().
Any comments?
Deng-Cheng
