Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965020Ab3DKPBP (ORCPT ); Thu, 11 Apr 2013 11:01:15 -0400 Received: from mail-ve0-f175.google.com ([209.85.128.175]:52382 "EHLO mail-ve0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756084Ab3DKPBO (ORCPT ); Thu, 11 Apr 2013 11:01:14 -0400 Message-ID: <5166D037.6040405@gmail.com> Date: Thu, 11 Apr 2013 11:01:11 -0400 From: KOSAKI Motohiro User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:17.0) Gecko/20130307 Thunderbird/17.0.4 MIME-Version: 1.0 To: Minchan Kim CC: KOSAKI Motohiro , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michael Kerrisk , Arun Sharma , John Stultz , Mel Gorman , Hugh Dickins , Dave Hansen , Rik van Riel , Neil Brown , Mike Hommey , Taras Glek , KOSAKI Motohiro , KAMEZAWA Hiroyuki , Jason Evans , sanjay@google.com, Paul Turner , Johannes Weiner , Michel Lespinasse , Andrew Morton Subject: Re: [RFC v7 00/11] Support vrange for anonymous page References: <1363073915-25000-1-git-send-email-minchan@kernel.org> <5165CA22.6080808@gmail.com> <20130411065546.GA10303@blaptop> <5166643E.6050704@gmail.com> <20130411080243.GA12626@blaptop> <5166712C.7040802@gmail.com> <20130411083146.GB12626@blaptop> In-Reply-To: <20130411083146.GB12626@blaptop> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1073 Lines: 24 >>>> and adding new syscall invokation is unwelcome. >>> >>> Sure. But one more system call could be cheaper than page-granuarity >>> operation on purged range. >> >> I don't think vrange(VOLATILE) cost is the related of this discusstion. >> Whether sending SIGBUS or just nuke pte, purge should be done on vmscan, >> not vrange() syscall. > > Again, please see the MADV_FREE. http://lwn.net/Articles/230799/ > It does changes pte and page flags on all pages of the range through > zap_pte_range. So it would make vrange(VOLASTILE) expensive and > the bigger cost is, the bigger range is. This haven't been crossed my mind. now try_to_discard_one() insert vrange for making SIGBUS. then, we can insert pte_none() as the same cost too. Am I missing something? I couldn't imazine why pte should be zapping on vrange(VOLATILE). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/