Re: [perfmon] Re: [perfmon2] perfmon2 merge news

[Nick Piggin <nickpiggin@yahoo.com.au>]

On Wednesday 14 November 2007 22:44, Paul Mackerras wrote:
> David Miller writes:
> > This is my impression too, all of the things being done with
> > a slew of system calls would be better served by real special
> > files and appropriate fops.
>
> Special files and fops really only work well if you can coerce the
> interface into one where data flows predominantly one way.  I don't
> think they work so well for something that is more like an RPC across
> the user/kernel barrier.  For that a system call is better.
>
> For instance, if you have something that kind-of looks like
>
> 	read_pmds(int n, int *pmd_numbers, u64 *pmd_values);
>
> where the caller supplies an array of PMD numbers and the function
> returns their values (and you want that reading to be done atomically
> in some sense), how would you do that using special files and fops?

Could you implement it with readv()?
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