From manningc2@actrix.gen.nz Wed Feb 03 00:15:42 2010 Received: from smtp.firstline.co.nz ([203.167.210.162] helo=firstline.co.nz) by stoneboat.aleph1.co.uk with smtp (Exim 4.69) (envelope-from ) id 1NcSu3-00081V-3G for yaffs@lists.aleph1.co.uk; Wed, 03 Feb 2010 00:15:42 +0000 Received: (qmail 25956 invoked by uid 453); 3 Feb 2010 00:15:16 -0000 X-Virus-Checked: Checked by ClamAV on firstline.co.nz Received: from Unknown (HELO linux-dual-head.local) (10.14.210.25) by firstline.co.nz (qpsmtpd/0.40) with ESMTP; Wed, 03 Feb 2010 13:15:16 +1300 From: Charles Manning To: yaffs@lists.aleph1.co.uk Date: Wed, 3 Feb 2010 13:15:15 +1300 User-Agent: KMail/1.9.10 References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <201002031315.15318.manningc2@actrix.gen.nz> X-SA-Exim-Connect-IP: 203.167.210.162 X-SA-Exim-Mail-From: manningc2@actrix.gen.nz X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on stoneboat.aleph1.co.uk X-Spam-Level: X-Spam-Status: No, score=-1.9 required=4.5 tests=AWL,BAYES_00,SPF_NEUTRAL autolearn=no version=3.2.5 X-SA-Exim-Version: 4.2.1 (built Wed, 25 Jun 2008 17:14:11 +0000) X-SA-Exim-Scanned: Yes (on stoneboat.aleph1.co.uk) Subject: Re: [Yaffs] multithreading question X-BeenThere: yaffs@lists.aleph1.co.uk X-Mailman-Version: 2.1.11 Precedence: list List-Id: Discussion of YAFFS NAND flash filesystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Feb 2010 00:15:42 -0000 On Tuesday 02 February 2010 00:29:17 Johan Kotlinski wrote: > Hi! > It appears that Yaffs2 multithreading protection is on a very high level > (mutex wrapping entire fread/fwrite calls). Are you talking about yaffs direct or the Linux yaffs? The linux yaffs will be locked on a page-by-page basis and I am going to change the way yaffs direct does the reading/writing too to only lock on a page-by-page basis. The underlying NAND is locked on a apge by page basis too (that's a limitation of the hardware), so is this really a big concern? > > My worry is that if a low-priority task does a large fwrite call, it could > block high-priority tasks for a long time. Is this an acknowledged problem? It depends on the OS. Some, without priority inhere, won't have this problem. > Are there comparable file systems that handle multithreading in a more > granular way?