Re: [RFC Patch V1 00/30] Enable memoryless node on x86 platforms

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


On 2014/7/22 1:57, Nishanth Aravamudan wrote:
> On 21.07.2014 [10:41:59 -0700], Tony Luck wrote:
>> On Mon, Jul 21, 2014 at 10:23 AM, Nishanth Aravamudan
>> <nacc@xxxxxxxxxxxxxxxxxx> wrote:
>>> It seems like the issue is the order of onlining of resources on a
>>> specific x86 platform?
>> Yes. When we online a node the BIOS hits us with some ACPI hotplug events:
>> First: Here are some new cpus
> Ok, so during this period, you might get some remote allocations. Do you
> know the topology of these CPUs? That is they belong to a
> (soon-to-exist) NUMA node? Can you online that currently offline NUMA
> node at this point (so that NODE_DATA()) resolves, etc.)?
Hi Nishanth,
	We have method to get the NUMA information about the CPU, and
patch "[RFC Patch V1 30/30] x86, NUMA: Online node earlier when doing
CPU hot-addition" tries to solve this issue by onlining NUMA node
as early as possible. Actually we are trying to enable memoryless node
as you have suggested.


>> Next: Here is some new memory
> And then update the NUMA topology at this point? That is,
> set_cpu_numa_node/mem as appropriate so the underlying allocators do the
> right thing?
>> Last; Here are some new I/O things (PCIe root ports, PCIe devices,
>> IOAPICs, IOMMUs, ...)
>> So there is a period where the node is memoryless - although that will
>> generally be resolved when the memory hot plug event arrives ... that
>> isn't guaranteed to occur (there might not be any memory on the node,
>> or what memory there is may have failed self-test and been disabled).
> Right, but the allocator(s) generally does the right thing already in
> the face of memoryless nodes -- they fallback to the nearest node. That
> leads to poor performance, but is functional. Based upon the previous
> thread Jiang pointed to, it seems like the real issue here isn't that
> the node is memoryless, but that it's not even online yet? So NODE_DATA
> access crashes?
> Thanks,
> Nish
To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at

[Index of Archives]     [Linux Kernel]     [Linux DVB]     [Asterisk Internet PBX]     [DCCP]     [Netdev]     []     [Util Linux NG]     [Fedora Women]     [ALSA Devel]     [Linux USB]

  Powered by Linux