From johan@teenageengineering.com Fri Feb 05 08:56:38 2010 Received: from n13.c03.server-system.net ([72.47.224.13]) by stoneboat.aleph1.co.uk with esmtp (Exim 4.69) (envelope-from ) id 1NdJzM-0008Dl-Td for yaffs@lists.aleph1.co.uk; Fri, 05 Feb 2010 08:56:38 +0000 Received: from [212.107.146.90] (port=48097 helo=johanxp) by n13.c03.server-system.net with esmtpa (Exim 4.63) (envelope-from ) id 1NdJz8-0002ZF-C2; Fri, 05 Feb 2010 00:56:20 -0800 Message-ID: From: "Johan Kotlinski" To: "Charles Manning" , References: <201002031315.15318.manningc2@actrix.gen.nz> <1E649C6B5AD2421E8F058091B48989A0@johanxp> <201002051705.56126.manningc2@actrix.gen.nz> Date: Fri, 5 Feb 2010 09:56:15 +0100 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Authenticated-User: 48231 johan@teenageengineering.com X-SA-Exim-Connect-IP: 72.47.224.13 X-SA-Exim-Mail-From: johan@teenageengineering.com X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on stoneboat.aleph1.co.uk X-Spam-Level: X-Spam-Status: No, score=-1.6 required=4.5 tests=AWL, BAYES_00, STOX_REPLY_TYPE 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: Fri, 05 Feb 2010 08:56:38 -0000 Very nice! We will try to integrate it in time. Thanks a lot for fast response! Regards Johan ----- Original Message ----- From: "Charles Manning" To: Cc: "Johan Kotlinski" Sent: Friday, February 05, 2010 5:05 AM Subject: Re: [Yaffs] multithreading question > On Wednesday 03 February 2010 23:17:42 Johan Kotlinski wrote: >> Hi Charles! >> >> Thanks for your answer. Yes, I was talking about yaffs direct. >> Page-by-page >> locking is of course all right. >> >> I have another question. Our NAND chip has the ability to prefetch pages. >> I >> imagine we could benefit from this. Is there a way to get a hint from >> yaffs >> what it is about to read next? Or do you know some good place to insert >> such an optimization? >> >> Best regards, >> Johan >> > I have just checked in code which breaks up long reads and writes into > smaller > sub read/writes. > > This has the advantage of reducing longing times. > > Please give this a whirl if it is of interest to you. > > -- Charles > > > ----- Original Message ----- >> From: "Charles Manning" >> To: >> Cc: "Johan Kotlinski" >> Sent: Wednesday, February 03, 2010 1:15 AM >> Subject: Re: [Yaffs] multithreading question >> >> > 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? >> >> _______________________________________________ >> yaffs mailing list >> yaffs@lists.aleph1.co.uk >> http://lists.aleph1.co.uk/cgi-bin/mailman/listinfo/yaffs > > >