Red Hat Linux 7.1: The Official Red Hat Linux Getting Started Guide | ||
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My computer has 128 MB of RAM, but I'm not sure all of it is being used. How can I find out whether all the RAM is being used? Is there a way to get Linux to recognize all my memory, if it isn't already?
Usually, the Linux kernel will recognize all of the RAM on a system; however, there may be circumstances in which not all of the memory is being recognized.
There is more than one way to make certain that all of your machine's memory is being used by the Linux kernel. First, test to see if all of your RAM is being used. If it is not, you can either enter an option at the boot: prompt every time you boot your machine or you can edit /etc/lilo.conf. If you edit /etc/lilo.conf, you will not have to add any options at boot time.
To see if the Linux kernel recognizes all of the RAM on your machine, at a shell prompt, type cat /proc/meminfo to find out the current statistics about memory usage on your system. Your output will probably look similar to the following:
total: used: free: shared: buffers: cached: Mem: 64655360 63033344 1622016 51159040 1552384 33816576 Swap: 73990144 700416 73289728 MemTotal: 63140 kB MemFree: 1584 kB MemShared: 49960 kB Buffers: 1516 kB Cached: 33024 kB SwapTotal: 72256 kB SwapFree: 71572 kB |
Among the categories you'll see will be the total amount of memory the Linux kernel recognizes (in the Mem: field). If, for example, you have 128 MB of RAM, and you see the Mem: entry reporting only 64 MB or so, then you should instruct the kernel to use all the RAM on your system.
You can pass the instruction to the kernel at the LILO
boot: prompt. Reboot your system (if you boot
directly to X,
you will need to press
boot: linux mem=128M |
Once you press
su to root and use Pico or your favorite text editor to edit /etc/lilo.conf. In /etc/lilo.conf, you'll see the following:
boot=/dev/hda map=/boot/map install=/boot/boot.b prompt timeout=50 image=/boot/vmlinuz-2.2.5-15 label=linux root=/dev/hda1 read-only |
Type in the following text as the first line: append="mem=128M". With the addition, the file should look something like this:
append="mem=128M" boot=/dev/hda map=/boot/map install=/boot/boot.b prompt timeout=50 image=/boot/vmlinuz-2.2.5-15 label=linux root=/dev/hda1 read-only |
You can use the
You'll be asked if you want to save the file; select
Now, type /sbin/lilo at the prompt to restart LILO. To exit the root account, type exit.
When you reboot, your memory configuration will be passed to the kernel.