> -----Original Message----- > From: Paolo Bonzini [mailto:pbonzini@xxxxxxxxxx] > Sent: Tuesday, November 24, 2015 10:38 PM > To: Radim Krcmár <rkrcmar@xxxxxxxxxx>; Wu, Feng <feng.wu@xxxxxxxxx> > Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] KVM: x86: Add lowest-priority support for vt-d posted- > interrupts > > > > On 24/11/2015 15:35, Radim Krcmár wrote: > > > Thanks for your guys' review. Yes, we can introduce a module option > > > for it. According to Radim's comments above, we need use the > > > same policy for PI and non-PI lowest-priority interrupts, so here is the > > > question: for vector hashing, it is easy to apply it for both non-PI and PI > > > case, however, for Round-Robin, in non-PI case, the round robin counter > > > is used and updated when the interrupt is injected to guest, but for > > > PI case, the interrupt is injected to guest totally by hardware, software > > > cannot control it while interrupt delivery, we can only decide the > > > destination vCPU for the PI interrupt in the initial configuration > > > time (guest update vMSI -> QEMU -> KVM). Do you guys have any good > > > suggestion to do round robin for PI lowest-priority? Seems Round robin > > > is not a good way for PI lowest-priority interrupts. Any comments > > > are appreciated! > > > > It's meaningless to try dynamic algorithms with PI so if we allow both > > lowest priority algorithms, I'd let PI handle any lowest priority only > > with vector hashing. (It's an ugly compromise.) > > For now, I would just keep the 4.4 behavior, i.e. disable PI unless > there is a single destination || vector hashing is enabled. We can flip > the switch later. Okay, let me try to understand this clearly: - We will have a new KVM command line parameter to indicate whether vector hashing is enabled. - If it is not enabled, for PI, we can only support single destination lowest priority interrupts, for non-PI, we continue to use RR. - If it is enabled, for PI and non-PI we use vector hashing for both of them. Is this the case you have in mind? Thanks a lot! Thanks, Feng > > Paolo ��.n��������+%������w��{.n�����o�^n�r������&��z�ޗ�zf���h���~����������_��+v���)ߣ�
