[Xen-devel] Re: turn off writable page tables

[Mike Day <ncmike@xxxxxxxxxx>]

On 28/07/06 10:21 -0500, Andrew Theurer wrote:

> So, in summary, we know writable page tables are not broken, they just 
> don't help on typical workloads because the PTEs/page are so low.  
> However, they do hurt SMP guest performance.  If we are not seeing a 
> benefit today, should we turn it off?  Should we make it a compile time 
> option, with the default off?

Keep in mind that the time is upon us when all servers are SMP, and
soon we will see 8-way blades. If you believe that what we are
releasing this year will take 6-12 months to make it to production at
a customer's site, then we should be assuming that everything (even
laptops) are SMP.

Looking ahead to next year, it's not unlikely that the sweetspot for
running Xen will go up from 2-4 cores to 4-8 cores. As a result, I
think wpt should not be the default.


Mike

(In the best tradition of a hardware vendor who likes for everyone to
have the latest iron.)

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