From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx175.postini.com [74.125.245.175]) by kanga.kvack.org (Postfix) with SMTP id 9E9926B0044 for ; Thu, 20 Dec 2012 05:55:22 -0500 (EST) From: Roman Gushchin In-Reply-To: <1355984435.1374.3.camel@kernel-VirtualBox> References: <50C4B4E7.60601@intel.com> <50C6AB45.606@intel.com> <20121216021508.GA3629@dcvr.yhbt.net> <1355984435.1374.3.camel@kernel-VirtualBox> Subject: Re: resend--[PATCH] improve read ahead in kernel MIME-Version: 1.0 Message-Id: <1461356000918@webcorp1g.yandex-team.ru> Date: Thu, 20 Dec 2012 14:55:18 +0400 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=koi8-r Sender: owner-linux-mm@kvack.org List-ID: To: Simon Jeons , Eric Wong Cc: xtu4 , "linux-kernel@vger.kernel.org" , "linux-tip-commits@vger.kernel.org" , "linux-mm@kvack.org" , "di.zhang@intel.com" Hi Simon, 20.12.2012, 10:21, "Simon Jeons" : > On Sun, 2012-12-16 at 02:15 +0000, Eric Wong wrote: > >> ?xtu4 wrote: >>> ?resend it, due to format error >>> >>> ?Subject: [PATCH] when system in low memory scenario, imaging there is a mp3 >>> ??play, ora video play, we need to read mp3 or video file >>> ??from memory to page cache,but when system lack of memory, >>> ??page cache of mp3 or video file will be reclaimed.once read >>> ??in memory, then reclaimed, it will cause audio or video >>> ??glitch,and it will increase the io operation at the same >>> ??time. >> ?To me, this basically describes how POSIX_FADV_NOREUSE should work. > > Hi Eric, > > But why fadvise POSIX_FADV_NOREUSE almost do nothing? Why not set some > flag or other things for these use once data? Because, it's not clear how should it work in some cases. Do we expect one access? Should we track a page as accessed after any access (even if only one byte was read)? What should we do with already-cached pages? etc. IMHO, it will be better to introduce something like POSIX_FADV_DONTCACHE. Corresponding pages can be added (ratated) to the tail of the inactive LRU after copying data in read() internals, or after minor/major pagefault. > >> ?I would like to have this ability via fadvise (and not CONFIG_). >> >> ?Also, I think your patch has too many #ifdefs to be accepted. >> >> ?-- >> ?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 > > -- > 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 -- 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