The OProfile perf backend uses a static array to keep track of the
perf events on the system. When compiling with CONFIG_CPUMASK_OFFSTACK=y
&& SMP, nr_cpumask_bits is not a compile-time constant and the build
will fail with:
oprofile_perf.c:28: error: variably modified 'perf_events' at file scope
This patch uses NR_CPUs instead of nr_cpumask_bits for the array
initialisation. If this causes space problems in the future, we can
always move to dynamic allocation for the events array.
Cc: Matt Fleming <[email protected]>
Cc: Robert Richter <[email protected]>
Reported-by: Russell King - ARM Linux <[email protected]>
Signed-off-by: Will Deacon <[email protected]>
---
drivers/oprofile/oprofile_perf.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/oprofile/oprofile_perf.c b/drivers/oprofile/oprofile_perf.c
index da14432..efc4b7f 100644
--- a/drivers/oprofile/oprofile_perf.c
+++ b/drivers/oprofile/oprofile_perf.c
@@ -25,7 +25,7 @@ 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_cpumask_bits];
+static struct perf_event **perf_events[NR_CPUS];
static int num_counters;
/*
--
1.7.4.1
Robert,
On Fri, Jun 08, 2012 at 04:16:04PM +0100, Will Deacon wrote:
> The OProfile perf backend uses a static array to keep track of the
> perf events on the system. When compiling with CONFIG_CPUMASK_OFFSTACK=y
> && SMP, nr_cpumask_bits is not a compile-time constant and the build
> will fail with:
>
> oprofile_perf.c:28: error: variably modified 'perf_events' at file scope
>
> This patch uses NR_CPUs instead of nr_cpumask_bits for the array
> initialisation. If this causes space problems in the future, we can
> always move to dynamic allocation for the events array.
>
> Cc: Matt Fleming <[email protected]>
> Cc: Robert Richter <[email protected]>
> Reported-by: Russell King - ARM Linux <[email protected]>
> Signed-off-by: Will Deacon <[email protected]>
> ---
> drivers/oprofile/oprofile_perf.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/oprofile/oprofile_perf.c b/drivers/oprofile/oprofile_perf.c
> index da14432..efc4b7f 100644
> --- a/drivers/oprofile/oprofile_perf.c
> +++ b/drivers/oprofile/oprofile_perf.c
> @@ -25,7 +25,7 @@ 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_cpumask_bits];
> +static struct perf_event **perf_events[NR_CPUS];
> static int num_counters;
>
> /*
> --
> 1.7.4.1
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/.
Thanks,
Will
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.
-Robert
--
Advanced Micro Devices, Inc.
Operating System Research Center
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.
Great, thanks Robert.
Will
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 <[email protected]>
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 <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Robert Richter <[email protected]>
---
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
On Fri, Jun 22, 2012 at 03:42:31PM +0100, Robert Richter wrote:
> Will,
Hi Robert,
> 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 seems fine with and without CONFIG_CPUMASK_OFFSTACK, so:
Acked-by: Will Deacon <[email protected]>
Cheers,
Will