Re: [02/17][PATCH] Implement smp_call_function_mask for ia64 - V8

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Jes Sorensen wrote:
> Jeremy Fitzhardinge wrote:
>   
> > Jes Sorensen wrote:
> > This change has been on the x86 side for ages, and not even Ingo made a 
> > peep about it ;)
> >     
>
> Mmmm, last time I looked, x86 didn't scale to any interesting number
> of CPUs :-)
>   

Well, I guess you need all those CPUs if scanning a 64-word bitvector 
takes anything like the time it takes to do an IPI...

> I wasn't suggesting we shouldn't have both interfaces, merely
> questioning why adding what to me seems like an unnecessary performance
> hit for the classic case of the call.

I don't mind how many interfaces there are, so long as there only needs 
to be one place to hook to plug in the Xen version of 
smp_call_function_whatever.  Perhaps the answer is to just hook the IPI 
mechanism itself rather than the whole of smp_call_function_mask...

Have you looked at Jens Axboe's patches to make all this stuff a lot 
more arch-common?

   J
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