[PATCH 0/1] [Yakkety] UBUNTU: [Config] Increase the NR_CPUS to 8K for amd64 to support systems with a large number of cores.
seth.forshee at canonical.com
Tue Nov 29 16:56:01 UTC 2016
On Tue, Nov 22, 2016 at 08:35:17AM -0800, Brad Figg wrote:
> On Tue, Nov 22, 2016 at 03:49:25PM +0000, Colin Ian King wrote:
> > On 22/11/16 15:35, Brad Figg wrote:
> > > BugLink: http://bugs.launchpad.net/bugs/1579205
> > >
> > > Brad Figg (1):
> > > UBUNTU: [Config] Increase the NR_CPUS to 8K for amd64 to support
> > > systems with a large number of cores.
> > >
> > > debian.master/config/amd64/config.common.amd64 | 2 +-
> > > debian.master/config/annotations | 2 +-
> > > 2 files changed, 2 insertions(+), 2 deletions(-)
> > >
> > What's the overhead or impact of bumping this to 8K?
> > Colin
> I'm not sure. However, Tim looked at this once before and found it wasn't
> significant if I remember right. This patch is a resubmit of one that was
> submitted, applied and the dropped mistakenly.
According to the Kconfig documentation for NR_CPUS, "each supported CPU
adds approximately eight kilobytes to the kernel image." If we assume
that is correct we're talking ~64MB of extra RAM. I'd be surprised if
anyone is actually keeping that estimate up to date though.
Tim - I don't suppose you still have the number you came up with before?
It would be nice to have an idea - cloud people may be upset if it turns
out to be a lot.
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