Re: [PATCH 4/5] oprofile: Remove exit function for timer mode

Robert Richter
2011-10-19T18:08:13Z

See below for Some more comments after testing and reviewing the
code. Will send a new version with these comments incorporated.

-Robert

On 17.10.11 10:27:04, Robert Richter wrote:
> +static struct notifier_block __cpuinitdata nmi_timer_cpu_nb = {

The __cpuinitdata attribute causes a section mismatch, will fix it.

> + .notifier_call = nmi_timer_cpu_notifier
> +};

> +static int nmi_timer_setup(void)
> +{
> + int cpu, err;
> +
> + /* clock cycles per tick: */
> + nmi_timer_attr.sample_period = (u64)cpu_khz * TICK_NSEC / NSEC_PER_MSEC;

This is broken on 32 bit.

Will replace it with:

/* clock cycles per tick: */
period = (u64)cpu_khz * 1000;
do_div(period, HZ);
nmi_timer_attr.sample_period = period;

> + pr_info("sample_period: %lld, cpu_khz: %d, nsec/tick: %ld\n",
> + nmi_timer_attr.sample_period, cpu_khz, TICK_NSEC);

I will remove this pr_info().

> +
> + get_online_cpus();
> + err = register_cpu_notifier(&nmi_timer_cpu_nb);
> + if (err)
> + goto out;

> diff --git a/drivers/oprofile/oprof.c b/drivers/oprofile/oprof.c
> index f7cd069..af9cbea 100644
> --- a/drivers/oprofile/oprof.c
> +++ b/drivers/oprofile/oprof.c
> @@ -248,15 +248,21 @@ static int __init oprofile_init(void)
> /* always init architecture to setup backtrace support */
> err = oprofile_arch_init(&oprofile_ops);
>
> - timer_mode = err || timer; /* fall back to timer mode on errors */
> + timer_mode = err || timer;
> if (timer_mode) {
> if (!err)
> oprofile_arch_exit();
> - err = oprofile_timer_init(&oprofile_ops);
> - if (err)
> - return err;
> + /* no nmi timer mode if oprofile.timer is set: */
> + if (!timer)
> + err = op_nmi_timer_init(&oprofile_ops);

As nmi timer is initialized here, we can remove it in arch/x86. This
eases setup functions for x86.

> + /* fall back to timer mode on errors: */
> + if (err || timer)
> + err = oprofile_timer_init(&oprofile_ops);
> }
>
> + if (err)
> + return err;
> +
> err = oprofilefs_register();
> if (!err)
> return 0;

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