On Sun, May 20, 2012 at 2:32 PM, Gilboa Davara <gilboad@xxxxxxxxx> wrote: > On Sun, May 20, 2012 at 4:07 AM, Josh Boyer <jwboyer@xxxxxxxxxx> wrote: >> >> On Sat, May 19, 2012 at 02:54:33PM +0200, Xose Vazquez Perez wrote: >> > >> > >* Tue Jan 17 2012 Dave Jones <davej@xxxxxxxxxx> >> > >- Rawhide builds now use MAXSMP on x86. >> > >- For release builds, set x86-64 to support 64 CPUs. >> > > If larger systems become widespread, we can increase in an update. >> > >> > _today_ >> > >> > amd: 4sockets * 16cores = 64 >> >> Awesome. Got that covered still. >> >> > intel: 4sockets * 10cores * 2threads = 80 >> >> Which particular CPU/Motherboard combo is that, and how often do we see >> it in Fedora? >> >> I'm not opposed to bumping it up to 128 or something, but I'm curious >> how many people are actually going to see benefits. >> >> josh > > At least in my case I did run Fedora 12-16 on 4S and 8S machines to > test software scalability on (extreme) high-end hardware. > Though, IMHO anyone that's crazy enough to run Fedora on a high-end > 4S/8S machine is more than capable of rebuilding the kernel with > CONFIG_NR_CPUS 256... > > However, given the fact that x86_64 machines tend to be far less > memory constrained than i686 machines, I doubt that raising the limit > to 128 will cause too many issues. (Isn't NR_CPUS == 512 in el6?) It's even higher these days: grep NR_CPUS /boot/config-2.6.32-220.13.1.el6.x86_64 CONFIG_NR_CPUS=4096 I'm curious, has anyone measured what the memory overhead is of keeping NR_CPUS at 512? arch/x86/Kconfig says "This is purely to save memory - each supported CPU adds approximately eight kilobytes to the kernel image." If that's true, 512 cpus use 4MB, something I'm willing to live with on my 64bit servers. Thanks, Ruben _______________________________________________ kernel mailing list kernel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/kernel
