>> use the free and top commands [image: memory_usage.PNG]
Memory information during boot up is as follows: [image: memory.PNG] top command vs. memory information during boot up. I believe memory information during boot up should be used to determine what size DRAM is needed? On Monday, July 29, 2019 at 9:45:29 AM UTC-4, Robert Heller wrote: > > At Mon, 29 Jul 2019 05:56:00 -0700 (PDT) [email protected] > <javascript:> wrote: > > > > > > > > > A traditional embedded system boots from flash memory and code runs from > > flash memory. Usually application isn't copied to RAM, only read/write > > variables are copied to RAM. > > Does system running embedded Linux execute from RAM? > > > > A typical embedded Linux evaluation board running some Linux > distribution > > boots from SD card. I believe entire kernel code, rwdata, rodata, init, > > bss, etc. is copied to RAM and code execution occurs in RAM. Is that > > correct? > > > > I need to know what size DRAM I need for my embedded Linux system? If > > Linux distribution takes up 3GB in SD card. Then, does this mean I need > > 3GB DRAM? > > It depends... > > If your target system only runs some limited subset of program, no, of > course > not. What is taking up the 3GB on the SD card are things like the usuall > "zillion" utilities, libraries, and so on. Also, an embedded Linux > appliance > (like your router or Blu-Ray player), is going to use BusyBox rather than > have > a /bin and /usr/bin populated with all the usually little programs (ls, > cp, > mv, rm, etc.). Instead, /bin, /sbin, /usr/bin and /usr/sbin will have > links > to BusyBox. Basically, it is just like a Linux boot init "ramdisk" that > never > bothers to mount a real "root" file system and continues to a full > multi-user > boot with all the trimmings. > > Next time you fire up your Beagle Bone, use the free and top commands to > have > a look at what is running and how (RAM) memory is being used. For example, > my > Raspberry Pi fruitloops is currently using just under 1 GB of RAM, running > about 100 processes: > > Tasks: 109 total, 1 running, 60 sleeping, 0 stopped, 0 zombie > %Cpu(s): 0.0 us, 0.3 sy, 0.0 ni, 99.7 id, 0.0 wa, 0.0 hi, 0.0 si, > 0.0 st > KiB Mem: 948308 total, 908924 used, 39384 free, 142516 buffers > KiB Swap: 102396 total, 21248 used, 81148 free. 138932 cached > Mem > > It is also using 21GB of a 32GB SD card. This is Raspbian, and includes a > pretty typical Linux multi-user system, eg systemd, ssh server, X11, a > compilete native G++ toolchain and libraries, with multiple cross-build > G++ > toolchain and libraries, for Arduino (arm, avr, xtensa) and OpenMRN (arm), > along with a full LaTeX install, Doxygen, etc. -- this is my general > purpose > build box for both native Raspbian (and also Beagle Debian targets), and > for > various little MCUs: Avr, Arm (samd), and esp32 Arduino supported, and > various > ARM-based MCUs supported by OpenMRN. > > -- > Robert Heller -- 978-544-6933 > Deepwoods Software -- Custom Software Services > http://www.deepsoft.com/ -- Linux Administration Services > [email protected] <javascript:> -- Webhosting Services > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/1b7d940d-114f-45df-8f68-9b634af2213f%40googlegroups.com.
