On 05/20/2012 11:23 AM, Ruben Kerkhof wrote: > 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 This is from RHEL which has a markedly different user base than Fedora does. I remember setting this in RHEL based on a partner request who ships LARGE systems (4096 CPUs, many many many TB of memory). This is not the number you want for Fedora. > > I'm curious, has anyone measured what the memory overhead is of > keeping NR_CPUS at 512? I think we did that in RHEL. It is insignificant IIRC. I'll try and dig out some numbers... P. _______________________________________________ kernel mailing list kernel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/kernel
