RE: How to increase mbuf size in dpdk version 17.11

["Lombardo, Ed" <Ed.Lombardo@netscout.com>]

Hi Stephen,
The VM is configured to have 32 GB of memory.  
Will dpdk consume the 2GB of hugepage memory for the mbufs?  
I don't mind having less mbufs with mbuf size of 16K vs original mbuf size of 2K.

Thanks,
Ed

-----Original Message-----
From: Stephen Hemminger <stephen@networkplumber.org> 
Sent: Tuesday, March 1, 2022 2:57 PM
To: Lombardo, Ed <Ed.Lombardo@netscout.com>
Cc: users@dpdk.org
Subject: Re: How to increase mbuf size in dpdk version 17.11

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On Tue, 1 Mar 2022 18:34:22 +0000
"Lombardo, Ed" <Ed.Lombardo@netscout.com> wrote:

> Hi,
> I have an application built with dpdk 17.11.
> During initialization I want to change the mbuf size from 2K to 16K.
> I want to receive packet sizes of 8K or more in one mbuf.
> 
> The VM running the application is configured to have 2G hugepages.
> 
> I tried many things and I get an error when a packet arrives.
> 
> I read online that there is #define DEFAULT_MBUF_DATA_SIZE that I changed from 2176 to ((2048*8)+128), where 128 is for headroom.
> The call to rte_pktmbuf_pool_create() returns success with my changes.
> From the rte_mempool_dump() - "rx_nombuf" - Total number of Rx mbuf allocation failures.  This value increments each time a packet arrives.
> 
> Is there any reference document explaining what causes this error?
> Is there a user guide I should follow to make the mbuf size change, starting with the hugepage value?
> 
> Thanks,
> Ed

Did you check that you have enough memory in the system for the larger footprint?
Using 16K per mbuf is going to cause lots of memory to be consumed.