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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Problems with enabling hypervisor C and P-state control
On Mon, Oct 27, 2008 at 6:04 PM, Tian, Kevin <kevin.tian@xxxxxxxxx> wrote: >>From: Niraj Tolia [mailto:ntolia@xxxxxxxxx] >>Sent: Tuesday, October 28, 2008 2:01 AM >> >>On Thu, Oct 23, 2008 at 10:59 PM, Yu, Ke <ke.yu@xxxxxxxxx> wrote: >>> After discussing with Jinsong, we got the root cause. You >>are right, this is xen pm statistics logic issue. when the >>coordination type is SW_ANY, we only record the first CPU >>cpufreq change, the other 3 cores within the same dependency >>domain is ignored, so you only see one core changes every >>dependency domain. >>> >>> The attached patch fix this issue. could you please have a >>try? If it works in your platform, we will send out for >>applying in upstream. >> >>I just applied the patch and while xenpm might be doing the right >>thing, I am not completely sure. For example, if I launch a single >>VCPU VM, pin it to a core, and launch a CPU intensive task on it, ALL >>four cores on the socket are reported to switch into P0. However, from >>what I understand about this processor (Xeon E7330), only two of them >>should. Like vanilla Linux, the other two should be able to operate at >>independent voltage/frequency settings. Once again, I am not sure if >>this is xenpm's fault or if the underlying frequency control code >>isn't able to determine what CPUs need to switch frequency at the >>same time. >> > > Do you change any BIOS setting when comparing native Linux and > Xen? From the xen dmesg you posted last time: No, I did not change anything in the BIOS. However, when I run vanilla Linux w/ cpufreqd, cpufreq-info will only list two cores being tied together. This is with the 2.6.24-21 kernel provided with Ubuntu 8.04.1. # cpufreq-info cpufrequtils 002: cpufreq-info (C) Dominik Brodowski 2004-2006 Report errors and bugs to linux@xxxxxxxx, please. analyzing CPU 0: driver: acpi-cpufreq CPUs which need to switch frequency at the same time: 0 4 hardware limits: 1.60 GHz - 2.40 GHz available frequency steps: 2.40 GHz, 2.13 GHz, 1.87 GHz, 1.60 GHz available cpufreq governors: powersave, conservative, ondemand, userspace, performance current policy: frequency should be within 1.60 GHz and 1.60 GHz. The governor "powersave" may decide which speed to use within this range. current CPU frequency is 1.60 GHz. ... Cheers, NIraj > ... > (XEN) _PSD: num_entries=5 rev=0 domain=1 coord_type=253 num_processors=4 > ... > (XEN) _PSD: num_entries=5 rev=0 domain=2 coord_type=253 num_processors=4 > ... > (XEN) _PSD: num_entries=5 rev=0 domain=3 coord_type=253 num_processors=4 > ... > You can see that BIOS reports 4 processors in a dependent domain > with a SW_ANY coordination type. It means that any cpu within > given dependent domain changes freq, all the rest 3 cpus change too. > > Thanks, > Kevin > > -- Niraj Tolia, Researcher, HP Labs http://www.hpl.hp.com/personal/Niraj_Tolia/ _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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