Date: Tue, 10 Feb 2009 17:07:22 +0100 From: Bengt Ahlgren <bengta@sics.se> To: Ian Smith <smithi@nimnet.asn.au> Cc: freebsd-mobile@freebsd.org Subject: Re: Problems with ath at kern.hz=100 Message-ID: <uh7d4dql1hh.fsf@P142.sics.se> In-Reply-To: <20090210154047.N38905@sola.nimnet.asn.au> (Ian Smith's message of "Tue\, 10 Feb 2009 16\:13\:23 %2B1100 \(EST\)") References: <uh7iqnjzzi9.fsf@P142.sics.se> <20090210154047.N38905@sola.nimnet.asn.au>
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Ian Smith <smithi@nimnet.asn.au> writes: > On Mon, 9 Feb 2009, Bengt Ahlgren wrote: > > > I was changing kern.hz to 100 on my IBM X40 (Pentium-M) laptop to see > > whether that saves some battery, but ran into problems with ath not > > working properly. At first I thought that my hardware was failing, > > but changing hz back to 1000 solved the problem. I am running > > 7.1-RELEASE-p1 and have the following Atheros chip: > > > > Feb 9 11:13:10 P142 kernel: ath_hal: 0.9.20.3 (AR5210, AR5211, AR5212, RF5111, RF5112, RF2413, RF5413) > > Feb 9 11:13:10 P142 kernel: ath0: <Atheros 5212> mem 0xd0200000-0xd020ffff irq 11 at device 2.0 on pci2 > > Feb 9 11:13:10 P142 kernel: ath0: [ITHREAD] > > Feb 9 11:13:10 P142 kernel: ath0: WARNING: using obsoleted if_watchdog interface > > Feb 9 11:13:10 P142 kernel: ath0: Ethernet address: 00:05:4e:4e:1f:c7 > > Feb 9 11:13:10 P142 kernel: ath0: mac 5.6 phy 4.1 5ghz radio 1.7 2ghz radio 2.3 > > There's an order of magnitude room to move between 100 and 1000 Hz. > You could also try with maybe 250 or 500? I have been running with hz=250 for a while now without the problem occuring. > What speed is your Pentium-M? Are you using powerd? If so, what > minimum CPU freq does it drop back to (sysctl debug.cpufreq.lowest)? It is a 1200MHz. I have debug.cpufreq.lowest=600 in order to only use EST. I ran for a while at 1200MHz with no powerd and ath still stopped sending. > Sam has talked of a problem with ath (and maybe other) interrupt rates > overwhelming slow CPUs to the extent that userland (ie powerd) doesn't > get a look-in for a while, as I understand it. A fast CPU clocked back > to less than say 300MHz IS a slow CPU, until powerd gets to crank it up. > > You might find that rc.conf setting economy_cx_lowest="LOW" can save you > some battery, though this benefit seems somewhat processor-dependent. I tried with dev.cpu.0.cx_lowest=C1 (at 1200MHz), but with no difference - the problem is still there. Bengt
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