Date: Wed, 05 Nov 2008 17:30:09 -0800 From: Sam Leffler <sam@freebsd.org> To: Alexander Motin <mav@freebsd.org> Cc: freebsd-mobile@freebsd.org Subject: Re: RFC: powerd algorithms enhancements Message-ID: <491248A1.4040607@freebsd.org> In-Reply-To: <491208D3.2050901@FreeBSD.org> References: <491208D3.2050901@FreeBSD.org>
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The biggest problem I see with powerd is that when a system is running
with a reduced clock frequency interrupts are not processed at full
clock speed. This, for example, breaks the ath driver which can
generate interrupts very quickly when h/w MIB counters overflow in a
noisy environment. Because processing happens at the reduced frequency
until powerd gets to run it causes livelock (or perhaps powerd does not
raise the clock frequency because it's only accounting for user code--I
haven't looked).
There's been talk about temporarily boosting the clock frequency in the
kernel when processing interrupts.
Sam
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