On Thu, Oct 02, 2014 at 02:31:17PM +0200, Andrea Arcangeli wrote: > On Wed, Oct 01, 2014 at 05:36:11PM +0200, Peter Zijlstra wrote: > > For all these and the other _fast() users, is there an actual limit to > > the nr_pages passed in? Because we used to have the 64 pages limit from > > DIO, but without that we get rather long IRQ-off latencies. > > Ok, I would tend to think this is an issue to solve in gup_fast > implementation, I wouldn't blame or modify the callers for it. > > I don't think there's anything that prevents gup_fast to enable irqs > after certain number of pages have been taken, nop; and disable the > irqs again. > Agreed, I once upon a time had a patch set converting the 2 (x86 and powerpc) gup_fast implementations at the time, but somehow that never got anywhere. Just saying we should probably do that before we add callers with unlimited nr_pages. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>