From mboxrd@z Thu Jan 1 00:00:00 1970 From: Len Brown Subject: Re: Help! I lost my C4 states :-) Date: 03 Mar 2005 16:38:49 -0500 Message-ID: <1109885929.2103.813.camel@d845pe> References: <20050221081225.GA10848@message-id.gmane0305.slipkontur.de> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit In-Reply-To: <20050221081225.GA10848-l0tNAEGuAhhzZ8+rp42Dbp9+tswZ0GTaehPwdyo5hKaELgA04lAiVw@public.gmane.org> Sender: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: acpi-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Stefan Seyfried Cc: ACPI Developers , Dominik Brodowski List-Id: linux-acpi@vger.kernel.org On Mon, 2005-02-21 at 03:12, Stefan Seyfried wrote: > Hi, > > Just curious: > i'm tracking Linus-bk-head quite closely. In (late?) January, > i was able to get my DELL D600 into C4. It worked fine and it > even got me an estimated 15-30 extra minutes out of the battery > (usually it lasts ~3.5 hours, the projected time with C4 was more > like almost 4 hours). Although this is great (it is more than i > ever got from laptop_mode and spinning down the harddisk), it > suddenly stopped working in February. Now the machine almost > always stays in C2, it hardly enters C3 or C4. > > seife@strolchi:~> cat /proc/acpi/processor/CPU0/power > active state: C2 > max_cstate: C8 > bus master activity: 10000500 > states: > C1: type[C1] promotion[C2] demotion[--] latency[001] usage[00000010] > *C2: type[C2] promotion[C3] demotion[C1] latency[001] usage[107659165] > C3: type[C3] promotion[C4] demotion[C2] latency[085] usage[03505424] > C4: type[C3] promotion[--] demotion[C3] latency[185] usage[06231087] > > There is always some bus master activity which i have not been able to track > down. I tried unloading almost all modules, but it did not help. Of course > there is no sound running, no USB mouse attached etc. I have quiesced the > harddisk with laptop_mode and mounting filesystems noatime and commit=300. > > The only thing that i can think of what has changed in my setup is that we > changed to modular IDE device drivers, but i cannot really imagine how that > would produce more bus master activity. > > Any hints on how to track down what is causing bus master activity all the > time? > Has the calculation algorithm changed? Any default settings i could tweak? Did you notice a battery life decrease with this decrease in C4 residency? On January 20th we pushed Dominik's jiffies based bm_activity patch in drivers/acpi/processor_idle.c You might find that backing out that file a couple of revisions restores the previous behaviour. Just after that, I added a tunable that you can tweak -- with 1000 HZ, its default is all bits enabled, but you can reduce this bit mask to make the driver ignore less recent history: # echo 0 > /sys/module/processor/parameters/bm_history Will cause the processor driver to ignore the bus master activity completely. Note that this could cause a performance hit if there is BM activity since will just pop the system out of C4 and no instructions are executed during the transition out of C4. cheers, -Len ps. If you're tracking battery life, I'd be interested to know if you notice a difference between when you build with HZ=100 and HZ=1000. ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click