RFE: Increase NR_CPUS to 4096

["Jóhann B. Guðmundsson"]

On 07/15/2013 05:57 PM, Russ Anderson wrote:
> On Mon, Jul 15, 2013 at 01:41:05PM -0400, Prarit Bhargava wrote:
>> >On 07/15/2013 01:33 PM, "Jóhann B. Guðmundsson" wrote:
>>> > >On 07/15/2013 05:21 PM, Prarit Bhargava wrote:
>>>> > >>I've done some testing across various systems (both "large" and "small").
>>>> > >>Increasing NR_CPUS seems to have a negligible effect.  I see about a 1.1M
>>>> > >>increase in memory usage when switching between 128 cpus and 5120 cpus.  Since
>>>> > >>most systems ship with 4G or more these days, I cannot see an issue with
>>>> > >>consuming a small amount of memory like this.
>>>> > >>
>>>> > >>The current NR_CPUS in Fedora is 128 and the current NR_CPUS in RHEL7 is 5120.
>>>> > >>I do not see any reason that those values have to be different anymore.
>>>> > >>
>>>> > >>Thoughts/concerns?
>>> > >
>>> > >I guess the question here is anyone aware of anyone running Fedora with 128
>> >
>> >Yes - me.  And I have HW that exceeds that number.
>> >
>>> > >cpu's or for that matter 5120.
>> >
>> >Yes -- Russ, care to share some numbers?
> We have a 5120 cpu system: 128 blades, 2 sockets per blade, 10 cores per socket,
> 2 HyperThreads per core.  That system has 8 TB memory.
>
> We have another with 4096 cpus: 128 blades, 2 sockets per blade, 8 cores per
> socket, 2 HyperThreads per core.  That system has 16 TB memory.
>
> Many smaller ones in the 512-1024 cpu range.
>
> FWIW, RHEL6 is CONFIG_NR_CPUS=4096

And you are currently running Fedora on those systems?

JBG