linux-kernel - Re: [Openipmi-developer] modprobe ipmi

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Date:	Wed, 20 May 2009 11:34:11 -0500
From:	Corey Minyard <minyard@....org>
To:	Ferenc Wagner <wferi@...f.hu>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	openipmi-developer@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: Re: [Openipmi-developer] modprobe ipmi_si hangs under 2.6.30-rc5

Ferenc Wagner wrote:
> Corey Minyard <minyard@....org> writes:
>
>   
>> I know what is happening now.  Can you try the attached patch?  I'm
>> disabling the requeue and discarding the message when an IPMB message
>> is received before everything is initialized.  If you don't, the code
>> will not deliver any messages because something is already in the
>> queue.
>>     
>
> Yep, that fixed it, modprobe runs through now!
>   
Thanks for testing this.

>   
>> Ferenc Wagner wrote:
>>
>>     
>>> My concern is that it does something too often, not letting the CPU
>>> enter deep sleep states, perhaps.  Or is that also an artifact of
>>> debugging?
>>>       
>> No, it's an artifact of a lousy hardware interface.  Very few IPMI
>> interfaces support interrupts, so they have to be polled :(.
>>     
>
> I'd say this isn't an artifact but the sad truth itself.  Just out of
> interest, how often does the driver wake up to check the inteface?
>   
I'd have to agree.

When idle, the driver wakes up every 10ms to check for something on the 
driver.  When a message is in transit, it's every jiffie.

-corey
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