On Mon, 21 Jul 2008 17:27:36 -0400, John Baldwin <jhb_at_freebsd.org> wrote: > On Saturday 19 July 2008 09:00:22 pm Giorgos Keramidas wrote: >> Well, I did try the following after booting with both CPUs in C1 state: >> >> (1) hw.acpi.cpu.cx_lowest: C1 >> dev.cpu.0.cx_lowest: C1 >> dev.cpu.0.cx_lowest: C2 >> >> I left the laptop to boot with both CPUs in C1, and then after a >> while I manually set dev.cpu.0.cx_lowest=C2. This setup seems >> ok. I can see processes being scheduled on both cpu.0 and cpu.1 >> and there's no "freeze" when the laptop is idle. >> >> (2) hw.acpi.cpu.cx_lowest: C1 >> dev.cpu.0.cx_lowest: C1 >> dev.cpu.0.cx_lowest: C3 >> >> Same as above, only this time I set dev.cpu.0.cx_lowest=C3. >> >> (3) hw.acpi.cpu.cx_lowest: C1 >> dev.cpu.0.cx_lowest: C2 >> dev.cpu.0.cx_lowest: C2 >> >> Not ok. When the laptop stays idle for some time, it starts >> getting too slow to type stuff in a terminal, and after a while >> I get `calcru: runtime went backwards' messages. >> >> I don't know if being scheduled on cpu.1 when it is in C2/C3 state has >> any measurable impact on user processes. Should I leave the settings to >> option (1) or (2) above for a while? Is there any way to find out if >> this causes any problems? > > My guess is that when both CPUs are in C2 or lower, the local APIC > timer is getting shut off and that is why your box is no longer > responsive. Fixing this is doable, but not very easy currently. Thanks! I can live with at least one core being in C1. It was mostly an annoying thing that "used to work" and seemed to be broken when I had to replace the old dead laptop. Thanks to Alexandre's excellent help, I can keep working now. If there's any sort of patch or experimental thing I can test, or you happen to think of something that would be nice to try, count me in :)Received on Mon Jul 21 2008 - 22:53:30 UTC
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