* 3.1-rc2: CONFIG_NUMA Question
@ 2011-08-18 10:51 Justin Piszcz
2011-08-18 11:51 ` Américo Wang
0 siblings, 1 reply; 4+ messages in thread
From: Justin Piszcz @ 2011-08-18 10:51 UTC (permalink / raw)
To: linux-kernel; +Cc: linux-numa, Alan Piszcz
Hi,
I have a SuperMicro X8DTH-6F motherboard with 2 cpus it has NUMA options
in the BIOS; what parameters/should I be using for the NUMA options in the
kernel?
| | [*] Numa Memory Allocation and Scheduler Support | |
| | [ ] Old style AMD Opteron NUMA detection | |
| | [*] ACPI NUMA detection | |
| | [ ] NUMA emulation | |
| | (6) Maximum NUMA Nodes (as a power of 2) | |
Specifically, the maximum number of NUMA nodes? Will this help to
increase performance of large memory allocations/is there any downside
to enabling this feature?
Justin.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: 3.1-rc2: CONFIG_NUMA Question
2011-08-18 10:51 3.1-rc2: CONFIG_NUMA Question Justin Piszcz
@ 2011-08-18 11:51 ` Américo Wang
2011-08-18 11:59 ` Justin Piszcz
0 siblings, 1 reply; 4+ messages in thread
From: Américo Wang @ 2011-08-18 11:51 UTC (permalink / raw)
To: Justin Piszcz; +Cc: linux-kernel, linux-numa, Alan Piszcz
On Thu, Aug 18, 2011 at 6:51 PM, Justin Piszcz <jpiszcz@lucidpixels.com> wrote:
> Hi,
>
> I have a SuperMicro X8DTH-6F motherboard with 2 cpus it has NUMA options in
> the BIOS; what parameters/should I be using for the NUMA options in the
> kernel?
>
> | | [*] Numa Memory Allocation and Scheduler Support | |
> | | [ ] Old style AMD Opteron NUMA detection | |
> | | [*] ACPI NUMA detection | |
> | | [ ] NUMA emulation | |
> | | (6) Maximum NUMA Nodes (as a power of 2) | |
>
That is Intel processor, right? If so, the things you selected here are enough,
the rest two is not what you need.
> Specifically, the maximum number of NUMA nodes? Will this help to increase
> performance of large memory allocations/is there any downside
> to enabling this feature?
The max of NUMA nodes is specified by CONFIG_NODES_SHIFT,
in your case, it is 6, which means it supports up to 2^6 nodes.
If your hardware supports NUMA, yes, that certainly help to increase
the performance.
Thanks.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: 3.1-rc2: CONFIG_NUMA Question
2011-08-18 11:51 ` Américo Wang
@ 2011-08-18 11:59 ` Justin Piszcz
2011-08-19 19:25 ` David Rientjes
0 siblings, 1 reply; 4+ messages in thread
From: Justin Piszcz @ 2011-08-18 11:59 UTC (permalink / raw)
To: Américo Wang; +Cc: linux-kernel, linux-numa, Alan Piszcz
[-- Attachment #1: Type: TEXT/PLAIN, Size: 1470 bytes --]
On Thu, 18 Aug 2011, Américo Wang wrote:
> On Thu, Aug 18, 2011 at 6:51 PM, Justin Piszcz <jpiszcz@lucidpixels.com> wrote:
>> Hi,
>>
>> I have a SuperMicro X8DTH-6F motherboard with 2 cpus it has NUMA options in
>> the BIOS; what parameters/should I be using for the NUMA options in the
>> kernel?
>>
>> | | [*] Numa Memory Allocation and Scheduler Support | |
>> | | [ ] Old style AMD Opteron NUMA detection | |
>> | | [*] ACPI NUMA detection | |
>> | | [ ] NUMA emulation | |
>> | | (6) Maximum NUMA Nodes (as a power of 2) | |
>>
>
> That is Intel processor, right? If so, the things you selected here are enough,
Hi, yes-- two Intel Xeon E5645s.
> the rest two is not what you need.
Ok.
>
>> Specifically, the maximum number of NUMA nodes? Will this help to increase
>> performance of large memory allocations/is there any downside
>> to enabling this feature?
>
> The max of NUMA nodes is specified by CONFIG_NODES_SHIFT,
> in your case, it is 6, which means it supports up to 2^6 nodes.
Ok, is there any overhead having more than is needed?
>
> If your hardware supports NUMA, yes, that certainly help to increase
> the performance.
Nice, thanks.
Justin.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: 3.1-rc2: CONFIG_NUMA Question
2011-08-18 11:59 ` Justin Piszcz
@ 2011-08-19 19:25 ` David Rientjes
0 siblings, 0 replies; 4+ messages in thread
From: David Rientjes @ 2011-08-19 19:25 UTC (permalink / raw)
To: Justin Piszcz; +Cc: Américo Wang, linux-kernel, linux-numa, Alan Piszcz
On Thu, 18 Aug 2011, Justin Piszcz wrote:
> > The max of NUMA nodes is specified by CONFIG_NODES_SHIFT,
> > in your case, it is 6, which means it supports up to 2^6 nodes.
> Ok, is there any overhead having more than is needed?
>
Yeah, try to avoid going above 8 because that causes nodemasks that are
typically allocated on the stack of kernel text to be dynamically
allocated through the slab allocator to avoid the possibility of overflow.
I doubt you have the need for more than 64 nodes, so I'd highly recommend
leaving it at the default unless you want to debug or test some large
numa=fake settings.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2011-08-19 19:25 UTC | newest]
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2011-08-18 10:51 3.1-rc2: CONFIG_NUMA Question Justin Piszcz
2011-08-18 11:51 ` Américo Wang
2011-08-18 11:59 ` Justin Piszcz
2011-08-19 19:25 ` David Rientjes
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