On Tuesday 23 January 2007 16:00, Henrique de Moraes Holschuh wrote: > On Tue, 23 Jan 2007, Mike Perry wrote: > > Is there currently any way to disable busmastering or C3 transitions > > (without recompilation)? Or better: is it possible to make the system > > less eager to transition into C3 or otherwise reduce the frequency of > > these transitions? If I could just get the frequency of transitions to > > get out of the audible range, my life would be a lot better. > > Read http://thinkwiki.org/wiki/Problem_with_high_pitch_noises, it may have > the answers. Pretty good write-up. It is correct, you should try max_cstate. for n starting at 3 and decreasing until the stound stops: # echo n > /sys/module/processor/parameters/max_cstate BTW. what model Thinkpad do you have? The USB dependency is probably due to USB bus mastering causing the system to "pop" out of C3 to snoop the USB DMA traffic. On some older systems, this pops all the way to C0, and on newer systems it transparently pops to C2 and returns to C3 w/o waking the OS. You can get rid of it by disabling USB. But it sounds like in the full-on case you've got an issue even with USB disabled. Or sometimes you can bias the system to simply not enter C3 if it sees bus master traffic with # echo 0xFFFFFFFF > /sys/module/processor/parameters/bm_history Another thing to try building the kernel with CONFIG_HZ=100 -- which is what a kernel for most laptops should be using in the first place. cheers, -Len - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
