From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx172.postini.com [74.125.245.172]) by kanga.kvack.org (Postfix) with SMTP id 5840B6B004D for ; Sat, 21 Apr 2012 19:56:26 -0400 (EDT) Received: by dadn15 with SMTP id n15so17286560dad.30 for ; Sat, 21 Apr 2012 16:56:25 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20120420145856.GC24486@thunk.org> References: <1334863211-19504-1-git-send-email-tytso@mit.edu> <4F912880.70708@panasas.com> <1334919662.5879.23.camel@dabdike> <1334932928.13001.11.camel@dabdike> <20120420145856.GC24486@thunk.org> From: KOSAKI Motohiro Date: Sat, 21 Apr 2012 19:56:05 -0400 Message-ID: Subject: Re: [PATCH, RFC 0/3] Introduce new O_HOT and O_COLD flags Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Ted Ts'o Cc: James Bottomley , Lukas Czerner , Boaz Harrosh , linux-fsdevel@vger.kernel.org, Ext4 Developers List , linux-mm@kvack.org On Fri, Apr 20, 2012 at 10:58 AM, Ted Ts'o wrote: > On Fri, Apr 20, 2012 at 06:42:08PM +0400, James Bottomley wrote: >> >> I'm not at all wedded to O_HOT and O_COLD; I think if we establish a >> hint hierarchy file->page cache->device then we should, of course, >> choose the best API and naming scheme for file->page cache. =A0The only >> real point I was making is that we should tie in the page cache, and >> currently it only knows about "hot" and "cold" pages. > > The problem is that "hot" and "cold" will have different meanings from > the perspective of the file system versus the page cache. =A0The file > system may consider a file "hot" if it is accessed frequently --- > compared to the other 2 TB of data on that HDD. =A0The memory subsystem > will consider a page "hot" compared to what has been recently accessed > in the 8GB of memory that you might have your system. =A0Now consider > that you might have a dozen or so 2TB disks that each have their "hot" > areas, and it's not at all obvious that just because a file, or even > part of a file is marked "hot", that it deserves to be in memory at > any particular point in time. So, this have intentionally different meanings I have no seen a reason why fs uses hot/cold words. It seems to bring a confusion. But I don't know full story of this feature and I might be overlooking something. -- 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 internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org