From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Larmour To: "Reto.Bucher@elektrobit.ch" Cc: ecos-discuss@sources.redhat.com Subject: Re: [ECOS] Memory Footprint Date: Thu, 26 Jul 2001 00:12:00 -0000 Message-id: <3B5FC2C1.EE975AA3@redhat.com> References: <003101c11405$0aa78fb0$9d0ba8c0@elektrobit.ch> X-SW-Source: 2001-07/msg00808.html > "Reto.Bucher@elektrobit.ch" wrote: > > Hello! > > I'm currently evaluating different operating systems for embedded > systems. Therefore, memorysize is one major concern. > > + What minimal size of memory footprint can I expect when I need to > include a TCP/IP stack? Here's something I wrote before for the ARM: -=-=-=-=-=-=-=- >From some simple measurements, the difference between including and not including the stack appears to be about 121944 bytes code, 3944 bytes initialized data, and 296940 bytes BSS, 256K of which is networking buffers. The buffer size cannot be shrunk down to near 0 though. Hugo would know better what the minimal requirements for this are. I've quoted below some things he wrote before that indicate that 128K is almost certainly the absolute minimum, otherwise you may never receive 64K packets. So you can subtract 128K off that 296940 bytes BSS to give the minimum. And as he says, there will potentially be more overruns/lost data even with that minimum. This is for an app that includes read, write and select. Values may differ more with extra functions as large sections of the stack may be brought in due to selective linking. But probably not. -=-=-=-=-=-=-=- eCos needs very little above that. > + is eCos a hard real time system? No, it is soft real time. The reasoning is that a lot of people believe they want a hard real time system, when they actually don't require it (hard real time systems while more deterministic, tend to be a lot slower). Jifl -- Red Hat, Rustat House, Clifton Road, Cambridge, UK. Tel: +44 (1223) 271062 Maybe this world is another planet's Hell -Aldous Huxley || Opinions==mine Come to the Red Hat TechWorld open source conference in Brussels! Keynotes, techie talks and exhibitions http://www.redhat-techworld.com/