On 2016-11-23 17:00, Ralf Ramsauer wrote: > Hi Mark, > > On 11/23/2016 03:46 PM, Mark Rutland wrote: >> On Wed, Nov 23, 2016 at 01:52:22PM +0100, Ralf Ramsauer wrote: >>> Hi, >>> >>> I first noticed that on the LeMaker Hikey: After jailhouse is >>> (successfully) enabled, the CPU board gets incredibly hot (after a few >>> seconds), though the root Linux still idles and no cells are created so >>> far. When jailhouse is disabled again, it immediately cools down within >>> seconds. >> >> I suspect that the issue here is that jailhouse doesn't handle >> PSCI_CPU_SUSPEND, but the host kernel is trying to use PSCI_CPU_SUSPEND >> for idle, as the hikey dts has idle states. >> >> AFAICT, jailhouse will trap the SMC, but will immediately return >> PSCI_NOT_SUPPORTED, since psci_dispatch [1] doesn't have a case for >> PSCI_CPU_SUSPEND. The host then immediately tries PSCI again. We burn >> CPU cycles jumping back-and-forth when we should be idle. >> >> It should be possible to look under sysfs to see how many times a CPU >> entered/exited PSCI idle states. IIRC there's a directory under >> /sys/devices/system/cpu/cpu<N>/ with idle residency information. >> >> I think jailhouse needs to gain some PSCI_CPU_SUSPEND support. It should >> be able to at least use WFI safely, and ideally it would call into the >> real PSCI implementation for deeper states.
Good point! wfi would be simple and safe, but is going into deeper states side-effect free for other cores? That's always the major concern about power saving, not only on ARM... > thanks. That's the issue. These are the cell statistics with > CONFIG_ARM_CPUIDLE enabled: > > COUNTER SUM PER SEC > vmexits_psci 15521049 289782 > > So we were exiting almost 300k/sec because of PSCI. > > After disabling CONFIG_ARM_CPUIDLE: > vmexits_psci 0 0 > Thanks for confirming. It was off here all around. Jan > Thanks > Ralf >> >> Thanks, >> Mark. >> >> [1] >> https://github.com/siemens/jailhouse/blob/master/hypervisor/arch/arm-common/psci.c >> > -- Siemens AG, Corporate Technology, CT RDA ITP SES-DE Corporate Competence Center Embedded Linux -- You received this message because you are subscribed to the Google Groups "Jailhouse" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
