According to http://www.kernel.org/doc/Documentation/sysctl/vm.txt
"Note: the minimum value allowed for dirty_bytes is two pages (in bytes); any value lower than this limit will be ignored and the old configuration will be retained."
Better make that 8192
Also you could try lowering /proc/sys/vm/dirty_ratio
According to http:// www.kernel. org/doc/ Documentation/ sysctl/ vm.txt
"Note: the minimum value allowed for dirty_bytes is two pages (in bytes); any
value lower than this limit will be ignored and the old configuration will be
retained."
Better make that 8192
Also you could try lowering /proc/sys/ vm/dirty_ ratio