Re: [PATCH] x86,sched: Fix sched_smt_power_savings totally broken

[Arjan van de Ven]

On 1/10/2012 6:41 AM, Peter Zijlstra wrote:
> On Tue, 2012-01-10 at 06:32 -0800, Arjan van de Ven wrote:
>>
>> a very good default would be to keep all tasks on one package until half
>> the cores in the package are busy, and then start spreading out. 
> 
> Does that still make sense when there's strong NUMA preference? By
> forcing stuff on a single package you increase the number of remote
> memory fetches (which generally generate more stalls), also the memory
> controllers need to stay awake anyway.

the memory controllers need to stake regardless of what you do;
it's more a memory bandwidth kind of thing.

if you have an enormous numa factor (>= 10 or so), then you really need
a completely different policy I suspect.
Thankfully those are rare.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/