From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vc0-f172.google.com (mail-vc0-f172.google.com [209.85.220.172]) by kanga.kvack.org (Postfix) with ESMTP id 0A5A56B0035 for ; Sun, 27 Apr 2014 15:47:25 -0400 (EDT) Received: by mail-vc0-f172.google.com with SMTP id la4so7241069vcb.3 for ; Sun, 27 Apr 2014 12:47:24 -0700 (PDT) Received: from mail-ve0-x22f.google.com (mail-ve0-x22f.google.com [2607:f8b0:400c:c01::22f]) by mx.google.com with ESMTPS id b2si3147772vcy.10.2014.04.27.12.47.24 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 27 Apr 2014 12:47:24 -0700 (PDT) Received: by mail-ve0-f175.google.com with SMTP id oz11so6987408veb.6 for ; Sun, 27 Apr 2014 12:47:24 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20140427193355.GA17778@laptop.programming.kicks-ass.net> References: <1398393700.8437.22.camel@pasglop> <5359CD7C.5020604@zytor.com> <20140425135101.GE11096@twins.programming.kicks-ass.net> <20140426180711.GM26782@laptop.programming.kicks-ass.net> <20140427072034.GC1429@laptop.programming.kicks-ass.net> <20140427193355.GA17778@laptop.programming.kicks-ass.net> Date: Sun, 27 Apr 2014 12:47:23 -0700 Message-ID: Subject: Re: Dirty/Access bits vs. page content From: Linus Torvalds Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Hugh Dickins , "H. Peter Anvin" , Benjamin Herrenschmidt , Jan Kara , Dave Hansen , "linux-arch@vger.kernel.org" , linux-mm , Russell King - ARM Linux , Tony Luck On Sun, Apr 27, 2014 at 12:33 PM, Peter Zijlstra wrote: > > Oh, absolutely. I wasn't arguing it didn't need it. I was merely > pointing out that if one was to add to Linus' patch such that we'd only > do the force_flush for mapping_cap_account_dirty() we wouldn't need > extra things to deal with shmem. I think we can certainly add that check if we find out that it is indeed a performance problem. I *could* imagine loads where people mmap/munmap shmem regions at a high rate, but don't actually know of any (remember: for this to matter they also have to dirty the pages). In the absence of such knowledge, I'd rather not make things more complex than they already are. Linus -- 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/ . Don't email: email@kvack.org