Date: Thu, 26 Aug 2004 10:07:17 -0700 From: Nate Lawson <nate@root.org> To: Kevin Oberman <oberman@es.net> Cc: acpi@freebsd.org Subject: Re: Cx states not working on Dell Inspiron 8600 (Pentium M) Message-ID: <412E18C5.1010603@root.org> In-Reply-To: <20040826163734.49EBF5D04@ptavv.es.net> References: <20040826163734.49EBF5D04@ptavv.es.net>
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Kevin Oberman wrote: >>Date: Thu, 26 Aug 2004 11:42:08 +0200 >>From: Ulrich Spoerlein <q@uni.de> > >>Hello, >> >>I've been running CURRENT on this laptop since the gcc 3.4 import and >>the Cx states don't work (AFAICS). >> >>dmesg, kernel config, DSDT and ASL can be obtained from >>http://www.galgenberg.net/~q/freebsd >> >>No matter if I pull the AC-plug or not, I get this: >>hw.acpi.cpu.throttle_max: 8 >>hw.acpi.cpu.throttle_state: 8 >>hw.acpi.cpu.cx_supported: C1/1 C2/1 C3/85 C4/185 >>hw.acpi.cpu.cx_lowest: C4 >>hw.acpi.cpu.cx_usage: 0.00% 100.00% 0.00% 0.00% >> >>As a result the laptop runs rather hot and the battery life is limited >>(compared to Windows) >> >>Am I using the wrong semantics for cx_lowest or throttle_max? > > > The cx_usage is limited to C1 or C2 if USB is loaded. It's polling of > the bus for changes prevents the state from dropping to anything really > useful. If you don't always need USB, build a kernel without it and load > it as required. Good summary. Playing sound also causes BM activity although just loading the sound driver is fine. > What do you have in your rc.conf? The default for economy_throttle_state > is "HIGH" which is probably not what you want. Not knowing how fast your > CPU is or how you use it, I don't know where you want to set it. > > Try experimenting with: > sysctl hw.acpi.cpu.throttle_state=n > setting 'n' to values in the range of 1-8 and see where you think it's > reasonable to get work done without draining the battery. I use: > economy_throttle_state=4. Any lower and things start to get painful for > me. Yes, that's why the default values are HIGH for both on/offline. Throttling has a pretty big effect on performance (whereas Cx idling is almost completely transparent). I didn't want to give users a bad impression of FreeBSD performance and figured users could set it lower as necessary. Once I get cpufreq in (after 5.3), we'll have two additive ways of adjusting cpu performance. For instance, if you have 2 throttling levels (100%, 50%) and two perf states (500 and 1500 mhz), you'll actually have 4 values: 1500, 750, 500, 250. This is all set with a single sysctl. -Nate
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