On Wed, 17 Sep 2008 17:52:00 -0300 Edesio Costa e Silva <edesio@xxxxxxxxxxxxxxxx> wrote: > I am running Linux 32 bits (2.6.26.5-bigsmp) on a virtual machine with 64 GB > of RAM. When I try to create a large file, for example "dd if=/dev/null > of=/tmp/huge.file bs=1024k count=65536" the machine hangs when the file hits > 22 GB mark. I instrumented the kernel with the debug options and before the > hang I got a message "lowmem_reserve[]: 0 0 0 0". Any hints on how to tune > Linux to handle this configuration? The problem is that the kernel needs buffer heads and all kinds of other metadata to keep track of the page cache. This metadata needs to be addressable by kernel functions, which means it has to live in lowmem. With 64GB total memory, the 896MB of lowmem will be filled up quickly and the kernel will lock up. > P.S.: Switching to a 64 bit kernel is NOT an option. Switching to a 64 bit kernel is one of only two options. The second option is to rewrite part of the VM so less metadata is kept for page cache. Specifically, you will have to write code to reclaim buffer heads from page cache pages. -- All rights reversed. -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
