Re: single software TLB vs. multiple software TLBs (was RE: [Xen-ia64-devel] [PATCH] [Resend]Enable hash vtlb)

[Tristan Gingold <Tristan.Gingold@xxxxxxxx>]

Le Mercredi 12 Avril 2006 10:57, Dong, Eddie a écrit :
> Tristan:
>       You are probably avocating for the flexibility of hash TLB too from the
> issue :-) Yes, when multiple TLBs are supported, i.e. hash TLB here, those
> big guest page translations can be put into software TLB using gmfn (leave
> to future tuning). When it is inserted into machine TLB or VHPT, it can be
> breakdown to many small page size translations (up to the balance of
> performance and functionality).
No, you have to split and insert all entries!

> I.e. the machine rr4.ps could be 16KB for
> guest vrr4.ps=256M. Another point is that VHPT hash uses VPN and rid as
> hash index, here the VPN means 256M/16K=16K contiguous index. In this way
> the hash result will be not duplicated as if the hash table can accomodate
> 16K+ entries. So forward progress can be guaranteed by the software TLB +
> VHPT.
>
>       Hope this helpful!
Ok it makes sense.  If the VHPT is correctly sized it should work.
[Maybe comments should be added somewhere to avoid future problem].

Thanks
Tristan.


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