RFE: Increase NR_CPUS to 4096

[Prarit Bhargava]

On 07/22/2013 07:26 AM, "Jóhann B. Guðmundsson" wrote:
> 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?

<sigh>

Yes.  We want to run Fedora "full out" on these systems ... otherwise why would
we be asking?

P.

>