Re: [Xen-ia64-devel] [PATCH] [Resend]Enable hash vtlb

[Tristan Gingold <Tristan.Gingold@xxxxxxxx>]

Le Mercredi 12 Avril 2006 10:53, Xu, Anthony a écrit :
> From: Tristan Gingold
>
> >Sent: 2006年4月12日 16:38
> >To: Xu, Anthony; xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> >Subject: Re: [Xen-ia64-devel] [PATCH] [Resend]Enable hash vtlb
> >
> >Le Mercredi 12 Avril 2006 10:01, Xu, Anthony a écrit :
> >> From: Tristan Gingold [mailto:Tristan.Gingold@xxxxxxxx]
> >>
> >> >Sent: 2006年4月12日 15:53
> >> >To: Xu, Anthony; xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> >> >Subject: Re: [Xen-ia64-devel] [PATCH] [Resend]Enable hash vtlb
> >> >
> >> >Le Vendredi 07 Avril 2006 21:02, Xu, Anthony a écrit :
> >> >> Hash vTLB is intended to address SMP scalability for large system.
> >> >
> >> >If I understand correctly, the Hash vTLB patch doesn't handle itc whose
> >> > ps
> >> >
> >> > > rr.ps (there is a panic here).
> >>
> >> Correct, Hash vTLB doesn't handle multiple page sizes on the same
> >> region. Linux doesn't use multiple page sizes on the same region.
> >> Linux uses region 4 to handle hugetlb like 256M, rr4.ps is set to 256M.
> >>
> >> >After a few minutes of thinking, I don't see how this could be done.
> >> >Any hint ?
> >>
> >> Break this huge tlb into several small tlbs whose page size is equal to
> >> rr.ps.
> >
> >I am not sure this works.  During insertion an entry can erase another
> > entry from the same itc.  And if a fault occurs within the erased entry,
> > there is no forward progression!
>
> I assume there are collision chains :-)
... and we could keep them for SMP-g too ;-)

Tristan.


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