On Thu, Mar 10, 2016 at 01:36:34PM +0000, Wu, Feng wrote: > > > > -----Original Message----- > > From: Tian, Kevin > > Sent: Thursday, March 10, 2016 6:06 PM > > To: Jan Beulich <jbeul...@suse.com> > > Cc: Andrew Cooper <andrew.coop...@citrix.com>; Dario Faggioli > > <dario.faggi...@citrix.com>; David Vrabel <david.vra...@citrix.com>; > > GeorgeDunlap <george.dun...@citrix.com>; Lars Kurth <lars.ku...@citrix.com>; > > George Dunlap <george.dun...@eu.citrix.com>; Ian Jackson > > <ian.jack...@eu.citrix.com>; Wu, Feng <feng...@intel.com>; xen- > > de...@lists.xen.org; Konrad Rzeszutek Wilk <konrad.w...@oracle.com> > > Subject: RE: vmx: VT-d posted-interrupt core logic handling > > > > > > Hi, Jan, > > > > I'm thinking your earlier idea about evenly distributed list: > > > > -- > > Ah, right, I think that limitation was named before, yet I've > > forgotten about it again. But that only slightly alters the > > suggestion: To distribute vCPU-s evenly would then require to > > change their placement on the pCPU in the course of entering > > blocked state. > > -- > > > > Actually after more thinking, there is no hard requirement that > > the vcpu must block on the pcpu which is configured in 'NDST' > > of that vcpu's PI descriptor. What really matters, is that the > > vcpu is added to the linked list of the very pcpu, then when PI > > notification comes we can always find out the vcpu struct from > > that pcpu's linked list. Of course one drawback of such placement > > is additional IPI incurred in wake up path. > > > > Then one possible optimized policy within vmx_vcpu_block could > > be: > > > > (Say PCPU1 which VCPU1 is currently blocked on) > > - As long as the #vcpus in the linked list on PCPU1 is below a > > threshold (say 16), add VCPU1 to the list. NDST set to PCPU1; > > Upon PI notification on PCPU1, local linked list is searched to > > find VCPU1 and then VCPU1 will be unblocked on PCPU1; > > > > - Otherwise, add VCPU1 to PCPU2 based on a simple distribution > > algorithm (based on vcpu_id/vm_id). VCPU1 still blocks on PCPU1 > > but NDST set to PCPU2. Upon notification on PCPU2, local linked > > list is searched to find VCPU1 and then an IPI is sent to PCPU1 to > > unblock VCPU1; > > > > Feng, do you see any overlook here? :-) > > Kevin, thanks for the suggestion, it sounds a good idea, I will think > it a bit more and do some trials based on it.
Hey! I am curious how the trials went? This feature is pretty awesome and I am wondering what the next step is? Thanks! _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
