On Mon, 2 Nov 2015, Steinar H. Gunderson wrote:

> > Once the data is in the kernel, the rest of the procedure is basically
> > zero-copy.  The problem is getting it there from within your program.  
> > We currently don't have any support for zero-copy data submissions,
> > although it has been proposed a few times in the past.
> 
> Do you know if there's any plans to revive these proposals? I've seen them in
> the archives, too, but they all seem to have died down. It seems each stream
> costs me ~15% or so of one core (mostly in copy_user_enhanced_fast_string and
> memset_erms, which I suppose are about copying to user space), and I'm a bit
> strapped for CPU already.

I haven't heard of any plans.  And I don't remember whether the earlier 
proposals covered isochronous or were only for bulk transfers.

Alan Stern

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