buffer mem

Miles Roper (mroper@westcoastdhb.org.nz)
Thu, 26 Jun 2003 15:25:58 +1200


Hi,

Been searching around on the net for an answer to this and haven't found
much after several hours.

My question is optimising a 2.4.20 version of the kernel for a low memory
machine. One thing I've been trying to find out is how do you reduce the
amount of buffer mem,

doing a free

total used free shared buffers
Mem: 321448 35080 286368 0 4892
Swap: 0 0 0
Total: 321448 35080 286368

always returns a buffer of around 4000, I would like to reduce this to
around 1000, as the machine I'm compiling the kernel for (not the one above)
has 16 meg of memory. In the 2.2 kernel there was some parameters in
/proc/sys/vm called buffermem, in a lot of the documentation that ships with
2.4.20 talks about this, but after searching on the net it seems like these
were removed in the 2.4 kernel and only applies to 2.2

I've found some documentation on some embedded systems tips which is meant
to reduce kernel memory requirements and have made these changes

Description VARIABLE OLD
NEW File
Number of supported disks DK_MAX_MAJOR 16 4
include/linux/kernal_stat.h
Number of supported disks DK_MAX_DISK 16 4
include/linux/kernal_stat.h
Maximum block device driver number MAX_BLKDEV 255 40
include/linux/major.h
kmsg message log size LOG_BUF_MEM 16384 8192
kernel/printk.c
Maxium number of tty consoles MAX_NR_CONSOLES 63 10
include/linux/tty.h

So is there any other variables controlling the buffer mem, and/or any other
variables that can safely reduce the memory requirements.

Cheers

Miles
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