Re: [PATCH V2 4/4] sh: Use the perf-events backend for oprofile

[Robert Richter]

On 26.08.10 15:09:19, Matt Fleming wrote:
> Use the perf-events based wrapper for oprofile available in
> drivers/oprofile. This allows us to centralise the code to control
> performance counters.
> 
> Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxx>
> ---
> 
> Paul,
> 
> I dropped the CONFIG_PERF_EVENTS dependency from the Makefile in this
> version because to do anything useful we need perf events anyway.

Initialization should simply fail with a printk message for this case,
implement function stubs for the !CONFIG_PERF_EVENTS case instead in
the oprofile.h header file.

> 
>  arch/sh/oprofile/Makefile  |    2 +-
>  arch/sh/oprofile/common.c  |   96 ++++++++-----------------------------------
>  arch/sh/oprofile/op_impl.h |   33 ---------------
>  3 files changed, 19 insertions(+), 112 deletions(-)
>  delete mode 100644 arch/sh/oprofile/op_impl.h
> 
> diff --git a/arch/sh/oprofile/Makefile b/arch/sh/oprofile/Makefile
> index 4886c5c..e1015ae 100644
> --- a/arch/sh/oprofile/Makefile
> +++ b/arch/sh/oprofile/Makefile
> @@ -4,6 +4,6 @@ DRIVER_OBJS = $(addprefix ../../../drivers/oprofile/, \
>  		oprof.o cpu_buffer.o buffer_sync.o \
>  		event_buffer.o oprofile_files.o \
>  		oprofilefs.o oprofile_stats.o \
> -		timer_int.o )
> +		timer_int.o oprofile_perf.o )
>  
>  oprofile-y	:= $(DRIVER_OBJS) common.o backtrace.o
> diff --git a/arch/sh/oprofile/common.c b/arch/sh/oprofile/common.c
> index ac60493..f8d4a84 100644
> --- a/arch/sh/oprofile/common.c
> +++ b/arch/sh/oprofile/common.c
> @@ -17,71 +17,23 @@
>  #include <linux/init.h>
>  #include <linux/errno.h>
>  #include <linux/smp.h>
> +#include <linux/perf_event.h>

I don't see a reason why this must be included here.

It's only for sh_pmu_name() and sh_pmu_num_events(), so the interface
looks wrong here. It should be in oprofile_perf.c. The functions
should be generic non-arch perf code. See below.

>  #include <asm/processor.h>
> -#include "op_impl.h"
> -
> -static struct op_sh_model *model;
> -
> -static struct op_counter_config ctr[20];
>  
>  extern void sh_backtrace(struct pt_regs * const regs, unsigned int depth);
>  
> -static int op_sh_setup(void)
> -{
> -	/* Pre-compute the values to stuff in the hardware registers.  */
> -	model->reg_setup(ctr);
> -
> -	/* Configure the registers on all cpus.  */
> -	on_each_cpu(model->cpu_setup, NULL, 1);
> -
> -        return 0;
> -}
> -
> -static int op_sh_create_files(struct super_block *sb, struct dentry *root)
> -{
> -	int i, ret = 0;
> -
> -	for (i = 0; i < model->num_counters; i++) {
> -		struct dentry *dir;
> -		char buf[4];
> -
> -		snprintf(buf, sizeof(buf), "%d", i);
> -		dir = oprofilefs_mkdir(sb, root, buf);
> -
> -		ret |= oprofilefs_create_ulong(sb, dir, "enabled", &ctr[i].enabled);
> -		ret |= oprofilefs_create_ulong(sb, dir, "event", &ctr[i].event);
> -		ret |= oprofilefs_create_ulong(sb, dir, "kernel", &ctr[i].kernel);
> -		ret |= oprofilefs_create_ulong(sb, dir, "user", &ctr[i].user);
> -
> -		if (model->create_files)
> -			ret |= model->create_files(sb, dir);
> -		else
> -			ret |= oprofilefs_create_ulong(sb, dir, "count", &ctr[i].count);
> -
> -		/* Dummy entries */
> -		ret |= oprofilefs_create_ulong(sb, dir, "unit_mask", &ctr[i].unit_mask);
> -	}
> -
> -	return ret;
> -}
> -
> -static int op_sh_start(void)
> +static char *op_name_from_perf_name(const char *name)
>  {
> -	/* Enable performance monitoring for all counters.  */
> -	on_each_cpu(model->cpu_start, NULL, 1);
> +	if (!strcmp(name, "SH-4A"))
> +		return "sh/sh4a";
> +	if (!strcmp(name, "SH7750"))
> +		return "sh/sh7750";

With that implementation we always have to touch the code for new
cpus. Maybe we derive it from the perf name, e.g. making all lowercase
and removing dashes?

>  
> -	return 0;
> -}
> -
> -static void op_sh_stop(void)
> -{
> -	/* Disable performance monitoring for all counters.  */
> -	on_each_cpu(model->cpu_stop, NULL, 1);
> +	return NULL;
>  }
>  
>  int __init oprofile_arch_init(struct oprofile_operations *ops)
>  {
> -	struct op_sh_model *lmodel = NULL;
>  	int ret;
>  
>  	/*
> @@ -91,40 +43,28 @@ int __init oprofile_arch_init(struct oprofile_operations *ops)
>  	 */
>  	ops->backtrace = sh_backtrace;
>  
> -	/*
> -	 * XXX
> -	 *
> -	 * All of the SH7750/SH-4A counters have been converted to perf,
> -	 * this infrastructure hook is left for other users until they've
> -	 * had a chance to convert over, at which point all of this
> -	 * will be deleted.
> -	 */
> -
> -	if (!lmodel)
> -		return -ENODEV;
>  	if (!(current_cpu_data.flags & CPU_HAS_PERF_COUNTER))
>  		return -ENODEV;
>  
> -	ret = lmodel->init();
> -	if (unlikely(ret != 0))
> -		return ret;
> +	ops->setup		= oprofile_perf_setup;
> +	ops->create_files	= oprofile_perf_create_files;
> +	ops->start		= oprofile_perf_start;
> +	ops->stop		= oprofile_perf_stop;
> +	ops->cpu_type		= op_name_from_perf_name(sh_pmu_name());
>  
> -	model = lmodel;
> +	oprofile_perf_set_num_counters(sh_pmu_num_events());
>  
> -	ops->setup		= op_sh_setup;
> -	ops->create_files	= op_sh_create_files;
> -	ops->start		= op_sh_start;
> -	ops->stop		= op_sh_stop;
> -	ops->cpu_type		= lmodel->cpu_type;
> +	ret = oprofile_perf_init();

Instead of exporting all the functions above implement something like:

	name = op_name_from_perf_name(sh_pmu_name());
	num_events = sh_pmu_num_events();
	ret = oprofile_perf_init(ops, name, num_events);

We will then have only oprofile_perf_init() and oprofile_perf_exit()
as interface which is much cleaner.

-Robert

> +	if (ret != 0)
> +		return ret;
>  
>  	printk(KERN_INFO "oprofile: using %s performance monitoring.\n",
> -	       lmodel->cpu_type);
> +	       ops->cpu_type);
>  
>  	return 0;
>  }
>  
>  void oprofile_arch_exit(void)
>  {
> -	if (model && model->exit)
> -		model->exit();
> +	oprofile_perf_exit();
>  }

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

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