Large machine test ideas

[Attilio Rao]

2011/8/31 Sean Bruno <seanbru at yahoo-inc.com>:
> On Tue, 2011-08-30 at 17:11 -0700, Ivan Voras wrote:
>> On 29.8.2011. 20:15, John Baldwin wrote:
>>
>> > However, the SRAT code just ignores the table when it encounters an issue like
>> > this, it doesn't hang.  Something else later in the boot must have hung.
>>
>> Anyway... that machine can in its maximal configuration be populated
>> with eight 10-core CPUs, i.e. 80 physical / 160 logical, so here's a
>> vote from me to bump the shiny new cpuset infrastructure maximum CPU
>> count to 256 before 9.0.
>>
>> http://www.supermicro.com/products/system/5U/5086/SYS-5086B-TRF.cfm
>
> Doesn't that (MAXCPU) seriously impact VM usage, lock contention
> etc ... ?
>
> I mean, if we have 2 cpus in a machine, but MAXCPU is set to 256, there
> is a bunch of "lost" memory and higher levels of lock contention?
>
> I thought that attilio was taking a stab at enhancing this, but at the
> current time anything more than a value of 64 for MAXCPU is kind of a
> "caveat emptor" area of FreeBSD.

With newest current you can redefine MAXCPU in your kernel config, so
you don't need to bump the default value.
I think 64 as default value is good enough.

Removing MAXCPU dependency from the KBI is an important project
someone should adopt and bring to conclusion.

Thanks,
Attilio


-- 
Peace can only be achieved by understanding - A. Einstein