linux-kernel - Re: [tip:perf/core] x86/nmi: Push duration printk() to irq context

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Message-ID: <52FA5366.3020007@linux.intel.com>
Date:	Tue, 11 Feb 2014 08:44:22 -0800
From:	Dave Hansen <dave.hansen@...ux.intel.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	mingo@...nel.org, hpa@...or.com, linux-kernel@...r.kernel.org,
	tglx@...utronix.de, dzickus@...hat.com,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:perf/core] x86/nmi: Push duration printk() to irq context

On 02/11/2014 07:01 AM, Peter Zijlstra wrote:
> -	irq_work_queue(&perf_duration_work);
> +	if (!irq_work_queue(&perf_duration_work)) {
> +		early_printk("perf interrupt took too long (%lld > %lld), lowering "
> +			     "kernel.perf_event_max_sample_rate to %d\n",
> +			     avg_local_sample_len, allowed_ns >> 1,
> +			     sysctl_perf_event_sample_rate);
> +	}
>  }

That's a cool trick.  Works for me.
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