On 02/03/2015 04:21 PM, Michal Hocko wrote: > On Tue 03-02-15 11:16:00, Mel Gorman wrote: >> On Tue, Feb 03, 2015 at 09:19:15AM +0100, Vlastimil Babka wrote: > [...] >>> And if we agree that there is indeed no guarantee, what's the actual semantic >>> difference from MADV_FREE? I guess none? So there's only a possible perfomance >>> difference? >>> >> >> Timing. MADV_DONTNEED if it has an effect is immediate, is a heavier >> operations and RSS is reduced. MADV_FREE only has an impact in the future >> if there is memory pressure. > > JFTR. the man page for MADV_FREE has been proposed already > (https://lkml.org/lkml/2014/12/5/63 should be the last version AFAIR). I > do not see it in the man-pages git tree but the patch was not in time > for 3.19 so I guess it will only appear in 3.20. > Yikes! That patch was buried in the bottom of a locked filing cabinet in a disused lavatory. I unfortunately don't read every thread that comes my way, especially if it doesn't look like a man-pages patch (i.e., falls in the middle of an LKML thread that starts on another topic, and doesn't see linux-man@). I'll respond to that patch soon. (There are some problems that mean I could not accept it, AFAICT.) Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- 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>