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 >
