From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id EB3F66B0087 for ; Tue, 23 Nov 2010 18:49:51 -0500 (EST) Received: by gyg10 with SMTP id 10so457353gyg.14 for ; Tue, 23 Nov 2010 15:49:50 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20101123095053.GG19571@csn.ul.ie> References: <5d205f8a4df078b0da3681063bbf37382b02dd23.1290349672.git.minchan.kim@gmail.com> <20101122142109.2f3e168c.akpm@linux-foundation.org> <20101123095053.GG19571@csn.ul.ie> Date: Wed, 24 Nov 2010 08:49:49 +0900 Message-ID: Subject: Re: [RFC 2/2] Prevent promotion of page in madvise_dontneed From: Minchan Kim Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: Andrew Morton , linux-mm , LKML , Rik van Riel , KOSAKI Motohiro , Johannes Weiner , Nick Piggin List-ID: On Tue, Nov 23, 2010 at 6:50 PM, Mel Gorman wrote: > On Mon, Nov 22, 2010 at 02:21:09PM -0800, Andrew Morton wrote: >> On Sun, 21 Nov 2010 23:30:24 +0900 >> Minchan Kim wrote: >> >> > Now zap_pte_range alwayas promotes pages which are pte_young && >> > !VM_SequentialReadHint(vma). But in case of calling MADV_DONTNEED, >> > it's unnecessary since the page wouldn't use any more. >> > >> > If the page is sharred by other processes and it's real working set >> >> This patch doesn't actually do anything. =A0It passes variable `promote' >> all the way down to unmap_vmas(), but unmap_vmas() doesn't use that new >> variable. >> >> Have a comment fixlet: >> >> --- a/mm/memory.c~mm-prevent-promotion-of-page-in-madvise_dontneed-fix >> +++ a/mm/memory.c >> @@ -1075,7 +1075,7 @@ static unsigned long unmap_page_range(st >> =A0 * @end_addr: virtual address at which to end unmapping >> =A0 * @nr_accounted: Place number of unmapped pages in vm-accountable vm= a's here >> =A0 * @details: details of nonlinear truncation or shared cache invalida= tion >> - * @promote: whether pages inclued vma would be promoted or not >> + * @promote: whether pages included in the vma should be promoted or no= t >> =A0 * >> =A0 * Returns the end address of the unmapping (restart addr if interrup= ted). >> =A0 * >> _ >> >> Also, I'd suggest that we avoid introducing the term "promote". > > Promote also has special meaning for huge pages. Demoting or promoting a > page refers to changing its size. The same applies to the other patch - > s/demote/deactive/ s/promote/activate/ . Currently this is no confusion > within the VM but when Andrea's THP patches are merged, it'll become an > issue. Thanks for the information. > > -- > Mel Gorman > Part-time Phd Student =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= Linux Technology Center > University of Limerick =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 IB= M Dublin Software Lab > --=20 Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org