From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757781Ab1F0Jrc (ORCPT ); Mon, 27 Jun 2011 05:47:32 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:58810 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757642Ab1F0JpM (ORCPT ); Mon, 27 Jun 2011 05:45:12 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Message-ID: <4E085113.7060200@jp.fujitsu.com> Date: Mon, 27 Jun 2011 18:44:51 +0900 From: KOSAKI Motohiro User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; ja; rv:1.9.2.18) Gecko/20110616 Lightning/1.0b2 Thunderbird/3.1.11 MIME-Version: 1.0 To: P@draigBrady.com CC: andrea@betterlinux.com, akpm@linux-foundation.org, minchan.kim@gmail.com, riel@redhat.com, peterz@infradead.org, hannes@cmpxchg.org, kamezawa.hiroyu@jp.fujitsu.com, aarcange@redhat.com, hughd@google.com, jamesjer@betterlinux.com, marcus@bluehost.com, matt@bluehost.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC] fadvise: move active pages to inactive list with POSIX_FADV_DONTNEED References: <1308779480-4950-1-git-send-email-andrea@betterlinux.com> <4E03200D.60704@draigBrady.com> <4E081764.7040709@jp.fujitsu.com> <4E084AA7.2030701@draigBrady.com> In-Reply-To: <4E084AA7.2030701@draigBrady.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2011/06/27 18:17), Pádraig Brady wrote: > On 27/06/11 06:38, KOSAKI Motohiro wrote: >>> Hmm, What if you do want to evict it from the cache for testing purposes? >>> Perhaps this functionality should be associated with POSIX_FADV_NOREUSE? >>> dd has been recently modified to support invalidating the cache for a file, >>> and it uses POSIX_FADV_DONTNEED for that. >>> http://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=5f311553 >> >> This change don't break dd. dd don't have a special privilege of file cache >> dropping if it's also used by other processes. >> >> if you want to drop a cache forcely (maybe for testing), you need to use >> /proc/sys/vm/drop_caches. It's ok to ignore other processes activity because >> it's privilege operation. > > Well the function and privileges are separate things. > I think we've agreed that the new functionality is > best associated with POSIX_FADV_NOREUSE, > and the existing functionality with POSIX_FADV_DONTNEED. > > BTW, I don't think privileges are currently enforced > as I got root to cache a file here with: > # (time md5sum; sleep 100) < big.file > And a normal user was able to uncache with: > $ dd iflag=nocache if=big.file count=0 > Anyway as said, this is a separate "issue". I'm failed to see your point. Why does dd need to ignore other process activity? If no other process, this patch doesn't change any behavior. Isn't it? From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id 3C5D39000BD for ; Mon, 27 Jun 2011 05:45:13 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp (unknown [10.0.50.73]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id 91D793EE0C0 for ; Mon, 27 Jun 2011 18:45:10 +0900 (JST) Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 7B16245DE8F for ; Mon, 27 Jun 2011 18:45:10 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 5628545DE9B for ; Mon, 27 Jun 2011 18:45:10 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 4A4071DB803C for ; Mon, 27 Jun 2011 18:45:10 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.240.81.145]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 0FD231DB8038 for ; Mon, 27 Jun 2011 18:45:10 +0900 (JST) Message-ID: <4E085113.7060200@jp.fujitsu.com> Date: Mon, 27 Jun 2011 18:44:51 +0900 From: KOSAKI Motohiro MIME-Version: 1.0 Subject: Re: [PATCH RFC] fadvise: move active pages to inactive list with POSIX_FADV_DONTNEED References: <1308779480-4950-1-git-send-email-andrea@betterlinux.com> <4E03200D.60704@draigBrady.com> <4E081764.7040709@jp.fujitsu.com> <4E084AA7.2030701@draigBrady.com> In-Reply-To: <4E084AA7.2030701@draigBrady.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: P@draigBrady.com Cc: andrea@betterlinux.com, akpm@linux-foundation.org, minchan.kim@gmail.com, riel@redhat.com, peterz@infradead.org, hannes@cmpxchg.org, kamezawa.hiroyu@jp.fujitsu.com, aarcange@redhat.com, hughd@google.com, jamesjer@betterlinux.com, marcus@bluehost.com, matt@bluehost.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org (2011/06/27 18:17), Padraig Brady wrote: > On 27/06/11 06:38, KOSAKI Motohiro wrote: >>> Hmm, What if you do want to evict it from the cache for testing purposes? >>> Perhaps this functionality should be associated with POSIX_FADV_NOREUSE? >>> dd has been recently modified to support invalidating the cache for a file, >>> and it uses POSIX_FADV_DONTNEED for that. >>> http://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=5f311553 >> >> This change don't break dd. dd don't have a special privilege of file cache >> dropping if it's also used by other processes. >> >> if you want to drop a cache forcely (maybe for testing), you need to use >> /proc/sys/vm/drop_caches. It's ok to ignore other processes activity because >> it's privilege operation. > > Well the function and privileges are separate things. > I think we've agreed that the new functionality is > best associated with POSIX_FADV_NOREUSE, > and the existing functionality with POSIX_FADV_DONTNEED. > > BTW, I don't think privileges are currently enforced > as I got root to cache a file here with: > # (time md5sum; sleep 100) < big.file > And a normal user was able to uncache with: > $ dd iflag=nocache if=big.file count=0 > Anyway as said, this is a separate "issue". I'm failed to see your point. Why does dd need to ignore other process activity? If no other process, this patch doesn't change any behavior. Isn't it? -- 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