Re: 2.6.14-rc4-rt7

[William Weston]

On Wed, 26 Oct 2005, Steven Rostedt wrote:

> Here's a updated patch.
> 
> Index: linux-2.6.14-rc5-rt7/kernel/time/timeofday.c
> ===================================================================
> --- linux-2.6.14-rc5-rt7.orig/kernel/time/timeofday.c	2005-10-26 16:57:03.000000000 -0400
> +++ linux-2.6.14-rc5-rt7/kernel/time/timeofday.c	2005-10-26 22:10:32.000000000 -0400
> @@ -232,6 +232,12 @@
>  	unsigned long seq;
>  	ktime_t prev, now;
>  	nsec_t mc, prev_st, curr_st;
> +	unsigned long flags;
> +
> +	raw_local_irq_save(flags);
> +	prev = per_cpu(prev_mono_time, cpu);
> +	prev_st = per_cpu(prev_system_time, cpu);
> +	raw_local_irq_restore(flags);
>  
>  	/* atomically read __get_monotonic_clock_ns() */
>  	do {
> @@ -242,11 +248,7 @@
>  	} while (read_seqretry(&system_time_lock, seq));
>  
>  	ns_to_timespec(ts, mc);
> -
>  	now = timespec_to_ktime(*ts);
> -	prev = per_cpu(prev_mono_time, cpu);
> -
> -	prev_st = per_cpu(prev_system_time, cpu);
>  	curr_st = system_time;
>  
>  	if (ktime_cmp(now, <, prev)) {
> @@ -264,8 +266,12 @@
>  		ktime_to_timespec(ts, prev);
>  		return;
>  	}
> +
> +	raw_local_irq_save(flags);
>  	per_cpu(prev_mono_time, cpu) = now;
>  	per_cpu(prev_system_time, cpu) = system_time;
> +	raw_local_irq_restore(flags);
> +
>  	put_cpu();
>  }

Hi Steven.  I think you fixed it!

The xeon-smt box has been up for over 30 minutes with this patch, and no
warnings as of yet.  Also, 'rtc_wakeup -f 1024' is reporting a max jitter
of 131us (decent for this box considering its hardware induced latencies)
instead of the >500us jitter seen earlier.

I'll try the patch out on the athlon box (which does mostly audio/midi)
when I get home.


--ww
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