Re: How do you calculate DPDK mempool requirements?

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 5 Dec 2022 11:32:40 -0600
Dylan Baros <dcbaros@utexas.edu> wrote:

> How do you figure out what settings need to be used to correctly configure
> a DPDK mempool for your application?
> 
> Specifically using rte_pktmbuf_pool_create():
> 
> - n, the number of elements in the mbuf pool
> - cache_size
> - priv_size
> - data_room_size
> 
> EAL arguments:
> - n number of memory channels
> - r number of memory ranks
> - m amount of memory to preallocate at startup
> - in-memory no shared data structures
> - IOVA mode
> - huge-worker-stack
> 
> My setup:
> 
>    - 2 x Intel Xeon Gold 6348 CPU @ 2.6 Ghz
>       - 28 cores per socket
>       - Max 3.5 Ghz
>       - Hyperthreading disabled
>       - Ubuntu 22.04.1 LTS
>       - Kernel 5.15.0-53-generic
>       - Cores set to performance governor
>       - 4 x Sabrent 2TB Rocket 4 Plus in RAID0 Config
>       - 128 GB DDR4 Memory
>       - 10 1GB HugePages (Can change to what is required)
>    - 1 x Mellanox ConnectX-5 100gbe NIC
>       - 31:00.0 Ethernet controller: Mellanox Technologies MT27800 Family
>       [ConnectX-5]
>       - Firmware-version: 16.35.1012
>    - UDP Source:
>       - 100 gbe NIC
>       - 9000 MTU Packets
>       - ipv4-udp packets
> 
> Will be receiving 10GB/s UDP packets over a 100gbe link. Right now trying
> to get it working for 2GB/s to a single queue.
> 
> Reviewed the DPDK Programmers guide:
> https://doc.dpdk.org/guides/prog_guide/mempool_lib.html Also searched
> online but the resources seem limited. Would appreciate any help or a push
> in the right direction.
> 
> 
> Sincerely,
> 
> DB

Compute the maximum number of live memory elements in the system.
This depends on the NIC card and the queue depths.
Add some additional overhead for packets in flight.

Size of mbuf depends on MTU, amount of reserved private area etc.