Re: [PATCH 0/2] KVM: arm64: Reduce occurence of GICv4 doorbells on non-oversubscribed systems

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Nov 07, 2019 at 04:04:10PM +0000, Marc Zyngier wrote:
> As I was cleaning up some of the GICv4 code to make way for GICv4.1 it
> occured to me that we could drastically reduce the impact of the GICv4
> doorbells on systems that are not oversubscribed (each vcpu "owns" a
> physical CPU).
> 
> The technique borrows its logic from the way we disable WFE trapping
> when a vcpu is the only process on the CPU run-queue. If this vcpu is
> the target of VLPIs, it is then beneficial not to trap blocking WFIs
> and to leave the vcpu waiting for interrupts in guest state.
> 
> All we need to do here is to track whether VLPIs are associated to a
> vcpu (which is easily done by using a counter that we update on MAPI,
> DISCARD and MOVI).
> 
> It has been *very lightly* tested on a D05, and behaved pretty well in
> my limited test cases (I get almost no doorbell at all in the non
> oversubscribed case, and the usual hailstorm as soon as there is
> oversubscription). I'd welcome some testing on more current HW.
> 
Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxx>
_______________________________________________
kvmarm mailing list
kvmarm@xxxxxxxxxxxxxxxxxxxxx
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm



[Index of Archives]     [Linux KVM]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux