[Xen-devel] Re: [PATCH 1 of 4] mm: add a ptep_modify_prot transaction abstraction

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Benjamin Herrenschmidt wrote:
> > Which architecture are you interested in?  If it isn't x86, you can 
> > probably get anything past Linus ;)
> > I'll do some measurements to see what effect the batchable 
> > ptep_set_wrprotect() has on native.  If it's significant, I'll propose 
> > making it conditional on CONFIG_PARAVIRT.
> >     
> Oh, I mostly think about powerpc, I just wondered if I could re-use
> your new stuff in that context. Mostly idle thoughts at this stage, I
> haven't looked seriously.
>   
There are general-purpose hooks in the common code which architectures 
can implement however they like.  In x86-land we hook them up to pvops, 
but you can handle them however you want.
> I have an old patch set to batch forks (and mprotect etc...) TLB
> invalidations (which is what I really want to batch on powerpc, more
> than the actual PTE changes) that involves subtle changes to the
> batching mechanisms etc...
>   
Do you mean setting up batches of per-page tlb shootdowns rather than 
going a global tlb flush at the end?
   J

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