linux-kernel - Re: [PATCH] x86_64: dynamic MCE poll interval

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Message-Id: <20070427141908.114bfe5a.randy.dunlap@oracle.com>
Date:	Fri, 27 Apr 2007 14:19:08 -0700
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	"Tim Hockin" <thockin@...gle.com>
Cc:	ak@....de, vojtech@...e.cz, linux-kernel@...r.kernel.org,
	akpm@...gle.com
Subject: Re: [PATCH] x86_64: dynamic MCE poll interval

On Fri, 27 Apr 2007 13:51:28 -0700 Tim Hockin wrote:

> This is the third version of this patch.  The only change from the prior
> version is to use time_after_eq().
> 
> diff -pruN linux-2.6.20/arch/x86_64/kernel/mce.c
> linux-2.6.20+th/arch/x86_64/kernel/mce.c
> --- linux-2.6.20/arch/x86_64/kernel/mce.c	2007-04-27 10:01:02.000000000 -0700
> +++ linux-2.6.20+th/arch/x86_64/kernel/mce.c	2007-04-27 10:41:02.000000000 -0700
> @@ -349,17 +351,30 @@ static void mcheck_timer(struct work_str
>  	 * writes.
>  	 */
>  	if (notify_user && console_logged) {
> +		static unsigned long last_print = 0;

Don't need to init statics to 0...

> +		unsigned long now = jiffies;
> +
> +		/* if we logged an MCE, reduce the polling interval */
> +		next_interval = max(next_interval/2, HZ/100);
>  		notify_user = 0;
>  		clear_bit(0, &console_logged);
> -		printk(KERN_INFO "Machine check events logged\n");
> +		if (time_after_eq(now, last_print + (check_interval*HZ))) {
> +			last_print = now;
> +			printk(KERN_INFO "Machine check events logged\n");
> +		}
> +	} else {
> +		next_interval = min(next_interval*2, check_interval*HZ);
>  	}
> +
> +	schedule_delayed_work(&mcheck_work, next_interval);
>  }


---
~Randy
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