From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamie Lokier Subject: Re: [PATCH 00/10] AXFS: Advanced XIP filesystem Date: Fri, 22 Aug 2008 19:37:13 +0100 Message-ID: <20080822183713.GC24179@shareable.org> References: <48AD00C4.6060302@gmail.com> <20080821110749.GA1926@shareable.org> <6934efce0808210711t686a88eci6eb294dbb54d68fe@mail.gmail.com> <48AE0476.80109@snapgear.com> <20080822181314.GB24179@shareable.org> <6934efce0808221116w76a662b0t954b0922b69d3232@mail.gmail.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <6934efce0808221116w76a662b0t954b0922b69d3232@mail.gmail.com> Sender: linux-embedded-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Jared Hulbert Cc: Greg Ungerer , Linux-kernel@vger.kernel.org, linux-embedded@vger.kernel.org, linux-mtd , =?iso-8859-1?Q?J=F6rn?= Engel , tim.bird@am.sony.com, cotte@de.ibm.com, nickpiggin@yahoo.com.au Jared Hulbert wrote: > On Fri, Aug 22, 2008 at 11:13 AM, Jamie Lokier wrote: > > Greg Ungerer wrote: > >> One thing for sure is that many people who do non-MMU setups > >> are interested in XIP to get the space savings. These are very > >> often small devices with very constrained RAM and flash. (For > >> whatever it is worth single NOR flash only boards are common in > >> these smaller form factors :-) > > > > I'm using XIP on a device with 32MB RAM. The reason I use it is > > _partly_ to save RAM, partly because programs start about 10 times > > faster (reading NOR flash is slow and I keep the XIP region in RAM) > > What kind of NOR you using? That is not what I measure with fast > synchronous burst NOR's. I think the "fast" in "fast synchronous" gives it away :-) I'm using Spansion MirrorBit S29GL128N, which reads at about 0.6 MByte/s. Not because they're good, but because that's what the board I'm coding for has on it. I presume they were cheap and familiar to the board designers. (There is 32MB of RAM to play with after all.) So start a sequence of Busybox processes from a shell script is noticable, if it reads from NOR each time. Oh, and it's a 166MHz ARM, so it's quite capable of decompressing faster than the NOR can deliver. -- Jamie