From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 18132 invoked by alias); 13 Jul 2004 07:58:21 -0000 Mailing-List: contact ecos-discuss-help@ecos.sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: ecos-discuss-owner@ecos.sourceware.org Received: (qmail 18123 invoked from network); 13 Jul 2004 07:58:20 -0000 Received: from unknown (HELO mail.broadpark.no) (217.13.4.2) by sourceware.org with SMTP; 13 Jul 2004 07:58:20 -0000 Received: from famine (217-13-20-38.dd.nextgentel.com [217.13.20.38]) by mail.broadpark.no (Postfix) with ESMTP id 3736D17E2; Tue, 13 Jul 2004 09:58:50 +0200 (MEST) From: =?ISO-8859-1?Q?=D8yvind?= Harboe To: Andrew Lunn Cc: ecos-discuss@sources.redhat.com In-Reply-To: <20040713074052.GO18802@lunn.ch> References: <1089643331.3951.42.camel@famine> <20040713074052.GO18802@lunn.ch> Content-Type: text/plain; charset=iso-8859-1 Message-Id: <1089705498.5995.7.camel@famine> Mime-Version: 1.0 Date: Tue, 13 Jul 2004 07:58:00 -0000 Content-Transfer-Encoding: 8bit Subject: Re: [ECOS] JFFS2 eats memory X-SW-Source: 2004-07/txt/msg00168.txt.bz2 On Tue, 2004-07-13 at 09:40, Andrew Lunn wrote: > On Mon, Jul 12, 2004 at 04:42:11PM +0200, ?yvind Harboe wrote: > > This issue has been discussed before, and although I have a workaround, > > I'd dearly like to have it put to bed since it is starting to cause > > problems elsewhere in my application: > > > > - My code opens a file for writing with O_TRUNC set, performs > > a single write call, closes the file. > > - After closing the file, JFFS2 has eaten memory. > > - With the attached modifcations to JFFS2, it "only" eats 24 bytes. > > - If I unmount and remount JFFS2, no memory is "lost" and JFFS2 works > > fine. > > > > Presumably when the raw nodes in the file fragement list are marked as > > obsolete, they are no longer required, but are not freed. > > > > Q: Is this fundamentally impossible or a "bad idea" to fix? > > How much memory are we talking about here in this example? 24 bytes* number of write() operations for each time a file is truncated. Additionally, memory is lost for other operations(e.g. deleting files), but I don't have any numbers(24 bytes for every time a file is deleted?). I'd really like to see that JFFS2 memory usage was constant if the number of files(and sections within those files) is constant. That way I could just run my system and measure the maximum usage. > The cache is there for a reason, so i would not want to > unconditionally disable it. At least you need some CDL to control > between fat & fast and slow & slim. Is JFFS2 faster because it caches raw_node_ref's to deleted nodes? Sounds strange. The mount code simply ignores these nodes, which insinuates that caching these nodes does not help performance. > I would also suggest you consider extending the > CYGNUM_FS_JFFS2_RAW_NODE_REF_CACHE_POOL_SIZE concept to the inode > cache. You can then control the size of the cache. AFAICT, this setting is no help in this case, because all it would do is to cause JFFS2 operations to fail when running out of pool space instead of when running out of overall system memory. Further it would lock a piece of the overall system memory to JFFS2, making the global memory situation worse. > > Andrew -- Øyvind Harboe http://www.zylin.com -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss