On Friday 22 October 2010 03:22:02 Sven Joachim wrote: > On 2010-10-22 03:15 +0200, Andrew Reid wrote: > > I recently deployed some new many-core servers at work, with > > 48 cores each (4x 12 core AMD 6174s), and ran into an issue where > > the stock Debian kernel is compiled with CONFIG_NR_CPUS=32, > > meaning it will only use the first 32 cores that it sees. > > For the record, CONFIG_NR_CPUS has been increased to 512 (the maximum > supported upstream) in Squeeze.
This is good to know. When I built my own 2.6.26, I also noticed that the maximum value offered by the configurator was 256 -- we'll likely be seeing systems with that many cores within a few years, if current trends continue. > Basically, 32 is chosen a bit arbitrarily. But there are some problems > with high values of CONFIG_NR_CPUS: > > - each supported CPU adds about eight kilobytes to the kernel image, > wasting memory on most machines. > > - On Linux 2.6.28 (maybe all kernels prior to 2.6.29), module size blows > up: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=516709. -- A. -- Andrew Reid / rei...@bellatlantic.net -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/201010222008.44192.rei...@bellatlantic.net
