[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] linux 4.4 Regression: 100% cpu usage on idle pv guest under Xen with single vcpu.
On 11/30/2015 04:46 PM, Sander Eikelenboom wrote: On 2015-11-30 22:45, Konrad Rzeszutek Wilk wrote:On Sat, Nov 28, 2015 at 04:47:43PM +0100, Sander Eikelenboom wrote:Hi all, I have just tested a 4.4-rc2 kernel (current linus tree) + the tip tree pulled on top.Running this kernel under Xen on PV-guests with multiple vcpus goes well (onidle < 10% cpu usage),but a guest with only a single vcpu doesn't idle at all, it seems a kworkerthread is stuck: root 569 98.0 0.0 0 0 ? R 16:02 12:47 [kworker/0:1]Running a 4.3 kernel works fine with a single vpcu, bisecting would probably quite painful since there were some breakages this merge window with respectto Xen pv-guests.There are some differences in the diff's from booting a 4.3, 4.4-single,4.4-multi cpu boot:Boris has been tracking a bunch of them. I am attaching the latest set ofpatches I've to carry on top of v4.4-rc3.Hi Konrad, i will test those, see if it fixes all my issues and report back They shouldn't help you ;-( (and I just saw a message from you confirming this) The first one fixes a 32-bit bug (on bare metal too). The second fixes a fatal bug for 32-bit PV guests. The other two are code improvements/cleanup. Thanks :) -- SanderBetween 4.3 and 4.4-single: -NR_IRQS:4352 nr_irqs:32 16 +Using NULL legacy PIC +NR_IRQS:4352 nr_irqs:32 0 This is fine, as long as you have b4ff8389ed14b849354b59ce9b360bdefcdbf99c. -cpu 0 spinlock event irq 17 +cpu 0 spinlock event irq 1 This is strange. I wouldn't expect spinlocks to use legacy irqs. and later on: -hctosys: unable to open rtc device (rtc0) +rtc_cmos rtc_cmos: hctosys: unable to read the hardware clock+genirq: Flags mismatch irq 8. 00000000 (hvc_console) vs. 00000000 (rtc0)+hvc_open: request_irq failed with rc -16. +Warning: unable to open an initial console. between 4.4-single and 4.4-multi: Using NULL legacy PIC -NR_IRQS:4352 nr_irqs:32 0 +NR_IRQS:4352 nr_irqs:48 0 This is probably OK too since nr_irqs depend on number of CPUs.I think something is messed up with IRQ. I saw last week something from setup_irq() generating a stack dump (warninig) for rtc_cmos but it appeared harmless at that time and now I don't see it anymore. -boris and later on: -rtc_cmos rtc_cmos: hctosys: unable to read the hardware clock +hctosys: unable to open rtc device (rtc0)-genirq: Flags mismatch irq 8. 00000000 (hvc_console) vs. 00000000 (rtc0)-hvc_open: request_irq failed with rc -16. -Warning: unable to open an initial console. attached: - dmesg with 4.3 kernel with 1 vcpu - dmesg with 4.4 kernel with 1 vpcu - dmesg with 4.4 kernel with 2 vpcus - .config of the 4.4 kernel is attached. -- Sander _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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