Re: [Xen-ia64-devel] Xen/IPF Unstable CS#18688, Linux#705, ioemu#629adb3f... Status --- no new issue, report 3 old bugs

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

On Mon, Oct 27, 2008 at 04:36:38PM +0800, Zhang, Xiantao wrote:
> Isaku Yamahata wrote:
> > On Fri, Oct 24, 2008 at 09:59:58AM +0800, Zhang, Jingke wrote:
> >>     3. IPF-Xen can not boot up domain with dom_id > 62 (not
> >> regression, should be there for a long time) 
> > 
> > Long ago, I posted the patch to address this issue.
> > Probably there are two ways. (Is there other better way?)
> > 
> > a.) abandon the rid partitioning, and flush mTLB every time vcpu
> >     context switch.
> 
> Current kvm adopts this method, we didn't find any performance regression 
> through benchmark. But sine the architecture difference between xen and kvm, 
> so maybe should investigate more through enough benchmark data. 

Sounds interesting.

> >     (some bits of rid space needs to be reserved for real mode
> > emulation.) 
> > 
> > b.) keep the rid partitioning and allow rid collision.
> >     When vcpu context switch, check the rid collision and
> >     flush mTLB if necessary.
> > 
> > Benchmark would be necessary to decide which one is better and
> > to estimate performance degradation.
> > I implemented b). However no one has implemented a).
> > So no further step was taken.
> 
> I thought Jingke isn't saying this  topic. What he found maybe he failed to 
> create the domain when the domain is created and destoryed continuously for 
> more 62 times. Seems the issue is from  the the algorithm for deallocating 
> rid blocks doesn't work, when destroying the guest.  

Oh I see. Thank you for the explanation.
-- 
yamahata

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