[dpdk-dev] Number of memory channels per processor socket?

[Keunhong Lee]

Currently, I have no idea to find out memory mapping of virtual machines.
I think -n 4 will work on both dual and quad channel memory.
This optimizes entries of mempool or ring structure to interleave memory
access into n-ways.
I think interleaving in 4 ways will also include 2 way interleaving.

Keunhong.

2015-06-29 8:46 GMT+09:00 Abhishek Verma <abhishekv.verma at gmail.com>:

> Thanks Keunhong.
>
> How do i get the motherboard spec on a virtual machine thats spawned on
> the cloud, for example Amazon EC2?
>
> Cheers, Abhishek
>
>
> On Mon, Jun 29, 2015 at 4:53 AM, Keunhong Lee <dlrmsghd at gmail.com> wrote:
>
>> See your motherboard spec.
>> For example, I'm using Intel 5930K with ASUS X99 Delux Motherboard (x99
>> chipset).
>> This site https://www.asus.com/us/Motherboards/X99DELUXE/specifications/
>> tells that
>> "Quad Channel Memory Architecture "
>> which means that "-n 4" is the correct configuration for me.
>>
>> To fully use quad channel memory, I have to use 4 separated DRAM,
>> installed on different memory slots of my motherboard.
>>
>> -n option optimizes memory bank access pattern for datastructures.
>> Since most motherboards support dual or quad memory channel,
>> -n 4 will work for most systems. (Only few motherboards support
>> tri-channel memory)
>>
>> I hope that this information is useful to you.
>> Keunhong.
>>
>>
>>
>> 2015-06-28 18:54 GMT+09:00 Abhishek Verma <abhishekv.verma at gmail.com>:
>>
>>> Hi,
>>>
>>> I am new to DPDK and i tried searching the archives in case this had been
>>> discussed but couldnt find any references and hence this email:
>>>
>>> What is the significance of " -n NUM: Number of memory channels per
>>> processor socket" which is passed as an EAL option? I have a virtual
>>> machine (VM) spawned using VirtualBox and i am trying to use DPDK to get
>>> faster access to packets there. I did lscpu, but that didnt give me
>>> anything interesting that i could use here:
>>>
>>> abhishekV at VirtualBox:~/dpdk/dpdk-2.0.0/x86_64-native-linuxapp-gcc/app$
>>> sudo
>>> lscpu
>>> [sudo] password for abhishekV:
>>>
>>> Architecture:          x86_64
>>> CPU op-mode(s):        32-bit, 64-bit
>>> Byte Order:            Little Endian
>>> CPU(s):                2
>>> On-line CPU(s) list:   0,1
>>> Thread(s) per core:    1
>>> Core(s) per socket:    2
>>> Socket(s):             1
>>> NUMA node(s):          1
>>> Vendor ID:             GenuineIntel
>>> CPU family:            6
>>> Model:                 58
>>> Stepping:              9
>>> CPU MHz:               2594.017
>>> BogoMIPS:              5188.03
>>> L1d cache:             32K
>>> L1d cache:             32K
>>> L2d cache:             6144K
>>> NUMA node0 CPU(s):     0,1
>>> abhishekV at VirtualBox:~/dpdk/dpdk-2.0.0/x86_64-native-linuxapp-gcc/app$
>>>
>>> I understand that i have two cores and hence should use -c 1 (since i
>>> have
>>> cores 0 and 1). However, i dont understand what to give as the "-n"
>>> option.
>>> Is it always 4?
>>>
>>> Thanks, Abhishek
>>>
>>
>>
>