Re: [RFC][PATCH 00/26] sched/numa

Avi Kivity
2012-03-20T10:19:11Z

On 03/19/2012 10:03 PM, Peter Zijlstra wrote:
> On Mon, 2012-03-19 at 14:16 +0200, Avi Kivity wrote:
> > > Afaik we do not use dma engines for memory migration.
> >
> > We don't, but I think we should.
>
> ISTR we (the community) had this discussion once. I also seem to
> remember the general consensus being that DMA engines would mostly
> likely not be worth the effort, although I can't really recall the
> specifics.
>
> Esp. for 4k pages the setup of the offload will likely be more expensive
> than actually doing the memcpy.

If you're copying a page, yes. If you're copying a large vma, the
per-page setup cost is likely to be very low.

Especially if you're copying across nodes.

--
error compiling committee.c: too many arguments to function