Re: [PATCH 2/2] tracing, perf : add cpu hotplug trace events
From: Vincent Guittot
Date: Thu Jan 27 2011 - 05:04:18 EST
On 26 January 2011 18:32, Frederic Weisbecker <fweisbec@xxxxxxxxx> wrote:
> On Tue, Jan 25, 2011 at 09:54:59AM +0100, Vincent Guittot wrote:
>> Please find below a new proposal for adding trace events for cpu hotplug.
>> The goal is to measure the latency of each part (kernel, architecture)
>> and also to trace the cpu hotplug activity with other power events. I
>> have tested these traces events on an arm platform.
>> Subject: [PATCH 1/2] add cpu hotplug tracepoints
>> this patch adds new events for cpu hotplug tracing
>> * plug/unplug sequence
>> * core and architecture latency measurements
>> Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
>> kernel/cpu.c | 17 +++++++++++++++++
>> 1 files changed, 17 insertions(+), 0 deletions(-)
>> diff --git a/kernel/cpu.c b/kernel/cpu.c
>> index 156cc55..f04e9cf 100644
>> --- a/kernel/cpu.c
>> +++ b/kernel/cpu.c
>> @@ -16,6 +16,9 @@
>> #include <linux/mutex.h>
>> #include <linux/gfp.h>
>> +#define CREATE_TRACE_POINTS
>> +#include <trace/events/cpu_hotplug.h>
>> #ifdef CONFIG_SMP
>> /* Serializes the updates to cpu_online_mask, cpu_present_mask */
>> static DEFINE_MUTEX(cpu_add_remove_lock);
>> @@ -200,7 +203,9 @@ static int __ref take_cpu_down(void *_param)
>> int err;
>> /* Ensure this CPU doesn't handle any more interrupts. */
>> + trace_cpu_hotplug_arch_disable_start((unsigned int)(param->hcpu));
>> err = __cpu_disable();
>> + trace_cpu_hotplug_arch_disable_end((unsigned int)(param->hcpu));
> You should create a cpu var instead of doing that not very beautiful cast
> Probably we should eventually rename arch_disable into just disable.
> And same for die, because otherwise the name is quite long.
If we remove the arch extension of these names, we will have
trace_cpu_hotplug_arch_up for __cpu_up (trace_cpu_hotplug_up is
already used) and trace_cpu_hotplug_disable for __cpu_disable. would
that be acceptable ?
> Other than that, looks all good to me.
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