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Subject[PATCH] oprofile, perf: Use per-cpu framework
Will,

On 15.06.12 17:19:54, Will Deacon wrote:
> On Fri, Jun 15, 2012 at 05:16:35PM +0100, Robert Richter wrote:
> > On 15.06.12 16:43:59, Will Deacon wrote:
> > > Given both the lack of feedback and the trivial nature of this patch would
> > > you be able to pick this up please? I'd rather not push it via the ARM tree
> > > as the change is under drivers/.
> >
> > Will, I will apply it. Sorry for not responding earlier.

I just realized I wrote a patch some time ago that introduces per_cpu
variables, see below. Please give it a try to, I will then queue it
for v3.6.

Your patch should go upstream anyway to make it into stable trees.

Thanks,

-Robert


From f8bbfd7d28303967ca4e8597de9bdc9bf8b197e7 Mon Sep 17 00:00:00 2001
From: Robert Richter <robert.richter@amd.com>
Date: Thu, 23 Feb 2012 17:07:06 +0100
Subject: [PATCH] oprofile, perf: Use per-cpu framework

This changes oprofile_perf.c to use the per-cpu framework.

Using the per-cpu framework should avoid error like the following:

arch/arm/oprofile/../../../drivers/oprofile/oprofile_perf.c:28:28: error: variably modified 'perf_events' at file scope

Reported-by: William Cohen <wcohen@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>
---
drivers/oprofile/oprofile_perf.c | 23 +++++++++++------------
1 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/drivers/oprofile/oprofile_perf.c b/drivers/oprofile/oprofile_perf.c
index efc4b7f..f3cfa0b 100644
--- a/drivers/oprofile/oprofile_perf.c
+++ b/drivers/oprofile/oprofile_perf.c
@@ -1,5 +1,6 @@
/*
* Copyright 2010 ARM Ltd.
+ * Copyright 2012 Advanced Micro Devices, Inc., Robert Richter
*
* Perf-events backend for OProfile.
*/
@@ -25,7 +26,7 @@ static int oprofile_perf_enabled;
static DEFINE_MUTEX(oprofile_perf_mutex);

static struct op_counter_config *counter_config;
-static struct perf_event **perf_events[NR_CPUS];
+static DEFINE_PER_CPU(struct perf_event **, perf_events);
static int num_counters;

/*
@@ -38,7 +39,7 @@ static void op_overflow_handler(struct perf_event *event,
u32 cpu = smp_processor_id();

for (id = 0; id < num_counters; ++id)
- if (perf_events[cpu][id] == event)
+ if (per_cpu(perf_events, cpu)[id] == event)
break;

if (id != num_counters)
@@ -74,7 +75,7 @@ static int op_create_counter(int cpu, int event)
{
struct perf_event *pevent;

- if (!counter_config[event].enabled || perf_events[cpu][event])
+ if (!counter_config[event].enabled || per_cpu(perf_events, cpu)[event])
return 0;

pevent = perf_event_create_kernel_counter(&counter_config[event].attr,
@@ -91,18 +92,18 @@ static int op_create_counter(int cpu, int event)
return -EBUSY;
}

- perf_events[cpu][event] = pevent;
+ per_cpu(perf_events, cpu)[event] = pevent;

return 0;
}

static void op_destroy_counter(int cpu, int event)
{
- struct perf_event *pevent = perf_events[cpu][event];
+ struct perf_event *pevent = per_cpu(perf_events, cpu)[event];

if (pevent) {
perf_event_release_kernel(pevent);
- perf_events[cpu][event] = NULL;
+ per_cpu(perf_events, cpu)[event] = NULL;
}
}

@@ -257,12 +258,12 @@ void oprofile_perf_exit(void)

for_each_possible_cpu(cpu) {
for (id = 0; id < num_counters; ++id) {
- event = perf_events[cpu][id];
+ event = per_cpu(perf_events, cpu)[id];
if (event)
perf_event_release_kernel(event);
}

- kfree(perf_events[cpu]);
+ kfree(per_cpu(perf_events, cpu));
}

kfree(counter_config);
@@ -277,8 +278,6 @@ int __init oprofile_perf_init(struct oprofile_operations *ops)
if (ret)
return ret;

- memset(&perf_events, 0, sizeof(perf_events));
-
num_counters = perf_num_counters();
if (num_counters <= 0) {
pr_info("oprofile: no performance counters\n");
@@ -298,9 +297,9 @@ int __init oprofile_perf_init(struct oprofile_operations *ops)
}

for_each_possible_cpu(cpu) {
- perf_events[cpu] = kcalloc(num_counters,
+ per_cpu(perf_events, cpu) = kcalloc(num_counters,
sizeof(struct perf_event *), GFP_KERNEL);
- if (!perf_events[cpu]) {
+ if (!per_cpu(perf_events, cpu)) {
pr_info("oprofile: failed to allocate %d perf events "
"for cpu %d\n", num_counters, cpu);
ret = -ENOMEM;
--
1.7.8.4


--
Advanced Micro Devices, Inc.
Operating System Research Center



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