linux-kernel - Re: [patch 2/2] x86: mce: Implement cmci poll mode for intel machines

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Date:	Tue, 5 Jun 2012 14:57:58 +0200
From:	Borislav Petkov <bp@...64.org>
To:	Chen Gong <gong.chen@...ux.intel.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>, tony.luck@...el.com,
	x86@...nel.org, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [patch 2/2] x86: mce: Implement cmci poll mode for intel machines

On Tue, Jun 05, 2012 at 07:47:20PM +0800, Chen Gong wrote:
> >  static void intel_threshold_interrupt(void)
> >  {
> > +	if (cmci_storm_detect())
> > +		return;
> >  	machine_check_poll(MCP_TIMESTAMP, &__get_cpu_var(mce_banks_owned));
> >  	mce_notify_irq();
> >  }
> 
> I think cmci_storm_detect should be placed in the machine_check_poll,
> not out of it. Because machine_check_poll it the core execution logic
> for CMCI handling, in the meanwhile, poll timer and mce-inject module
> call machine_check_poll at any time.

Are you saying you need CMCI throttling for when you inject MCEs?

> If poll timer or mce-inject run too quickly, the CMCI handler has
> trouble. Whereas, if cmci_storm_detect is in the machine_check_poll,
> this kind of possibility can be avoid.

In any case, cmci_storm_detect() cannot be in machine_check_poll because
last one is generic MCE code and not Intel-only. Unless you do something
like what Thomas proposed for mce_adjust_timer where the default
function does nothing and Intel only overwrites that pointer with the
needed functionality.

-- 
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Boris.

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