I just want to repeat some observations I made over time here: I have seen this on quite a few machines. Though solutions vary and I am not sure there is a good automated way yet. The basic problem is that using lower C-states has some effects on the timer tick sources normally used (lapic and tsc stop). In general, the kernel tries to detect that and use a broadcast mechanism that takes the timer device to fire an interrupt (irq0) when the kernel should wake up. On newer boards that timer is hardware emulated using the hpet.
In the simplest case, the bios does not initialize the chipset correctly. There is a acpi bios entry which tells the OS to which apic pin the timer is really connected to. Sometimes this is wrong and "acpi_skip_timer_override" does help. One way to test for it is to look at irq0 in /proc/interrupts. This number should increment at least on one cpu. But I have seen this odd case on my netbook, where the timer interrupt increments and still I had those weird issues with the system being stuck until I pressed a key. Which seems to be a strange case of the timer interrupt not being sufficient to wake up the system (which is something I still need to get explained by experts). In that case the i915 card also has the issue of not triggering interrupts on sync which usually seems to keep systems alive enough. Plus the other devices that usually keeps the system busy (ethernet and ahci) was using MSI interrupts, which also seems to insufficient. In this constellation "pci=nomsi" seems to help well enough as it causes enough other interrupts to be triggered. If nothing else helps, there might be a chance to prevent the system to go into the deeper c-states at all: "processor.max_cstate=<nr>" (or when intel_idle is used "intel_idle.max_cstate=<nr>"). One would see the result in powertop. This comes at the expense of higher power usage though. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/217849 Title: Hardy, Intrepid, Jaunty 64 "hiccup" on Sager notebook. -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
