linux-kernel - Re: forcedeth: option to disable 100Hz timer (try 2)

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Message-ID: <48C863CC.3010902@shaw.ca>
Date:	Wed, 10 Sep 2008 18:18:20 -0600
From:	Robert Hancock <hancockr@...w.ca>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Mikhail Kshevetskiy <mikhail.kshevetskiy@...il.com>,
	linux-kernel@...r.kernel.org, aabdulla@...dia.com,
	jgarzik@...ox.com
Subject: Re: forcedeth: option to disable 100Hz timer (try 2)

Andrew Morton wrote:
> On Tue, 9 Sep 2008 23:34:35 +0400
> Mikhail Kshevetskiy <mikhail.kshevetskiy@...il.com> wrote:
> 
>> On some hardware no TX done interrupts are generated, thus special
>> 100Hz timer interrupt is required to handle this situation properly.
>> Other device do not require that timer interrupt feature. 
>>
>> Forcedeth has a DEV_NEED_TIMERIRQ flag to mark the broken devices.
>> Unfortunately, nobody know the actual list of broken devices, so all
>> device has this flag on. Other problem, this flag is not user visible,
>> so the kernel recompilation is required to disable timer interrupts and
>> test a device.
>>
>> This patch add a "disable_timerirq" option to disable interrupt 
>> timer mentioned above. This may be extremely useful for laptop users.
> 
> Why do you feel that the timer-based completions need to be disabled? 
> Is it causing some problem?

100 unnecessary CPU wakeups per second imposes some power usage cost, 
especially on laptops with CPU C-states..

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