Nicolas Justin wrote: > > Le Lundi 15 Juillet 2002 22:45, Joseph A Knapka a écrit : > > > What is the maximum adressable memory for a user space process on the > > > same system ? > > > > 3G, unless you change the value of PAGE_OFFSET. > > Can I modify PAGE_OFFSET to increase the user space process adressable memory > (and so decrease the kernel space) ? > Can you give me more on informations on this ? Short answer: no. Long answer: the more physical memory you have, the more virtual space the kernel needs in order to manage it. Also, the kernel uses its virtual space for a number of other things (vmalloc allocates physical memory and maps it into otherwise-unused kernel virtual space; thus all kernel subsystems that use vmalloc may suffer if kernel virtual space is squeezed too much). The upshot is that on a 4G machine the kernel really needs 1G of virtual space to function properly. The memory map alone occupies 64MB of virtual space on a 4G machine. Cheers, -- Joe -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
