On 05/14/2012 11:01 PM, Christoph Lameter wrote: > On Mon, 14 May 2012, Peter Zijlstra wrote: > >> I'd say go for it, I've been telling everybody who would listen that >> mlock() only means no major faults for a very long time now. > > We could introduce a new page flag PG_pinned (it already exists for Xen) > that would mean no faults on the page? > > The situation with pinned pages is not clean right now because page count > increases should only signal temporary references to a page but subsystems > use an elevated page count to pin pages for good (f.e. Infiniband memory > registration). The reclaim logic has no way to differentiate between a > pinned page and a temporary reference count increase for page handling. > > Therefore f.e. the page migration logic will repeatedly try to move the > page and always fail to account for all references. > > A PG_pinned could allow us to make that distinction to avoid overhead in > the reclaim and page migration logic and also we could add some semantics > that avoid page faults. It does make sense! -- Kind regards, Minchan Kim -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>