From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: MADV_DONTNEED semantics? Was: [RFC PATCH] mm: madvise: Ignore repeated MADV_DONTNEED hints Date: Tue, 3 Feb 2015 16:21:21 +0100 Message-ID: <20150203152121.GC8914@dhcp22.suse.cz> References: <20150202165525.GM2395@suse.de> <54CFF8AC.6010102@intel.com> <54D08483.40209@suse.cz> <20150203111600.GR2395@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20150203111600.GR2395-l3A5Bk7waGM@public.gmane.org> Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mel Gorman Cc: Vlastimil Babka , Dave Hansen , linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Minchan Kim , Andrew Morton , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org 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. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html