On Mon, 13 Sep 2021 16:43:18 +0100
Ferruh Yigit <ferruh.yi...@intel.com> wrote:
> On 9/13/2021 5:56 AM, Kamaraj P wrote:
> > Hello All,
> >
> > Would like to understand or if there are any guidelines to allocate the max
> > no of mbuf per NIC ?
> > For example, if i have defined as below:
> > #define RX_RING_SIZE 1024
> > #define TX_RING_SIZE 1024
> >
> > The Maximum RX/TX queues can be defined as 8 per NIC, What would be the max
> > no of mbuf can be allocated per NIC ?
> > Please share if there is any guildliness or any limitation to increase the
> > mbuf ?
> >
>
> Hi Kamaraj,
>
> Max number of the queues and max number of the descriptors per queue depends
> to
> HW and changes form HW to HW.
> This information is shared by the PMDs that application needs to take into
> account. For example the descriptor limitations are provided by
> 'rx_desc_lim'/'tx_desc_lim' etc.
>
> After descriptor number is defined, testpmd uses the mbuf count as following,
> which can be taken as sample:
>
> nb_mbuf_per_pool = RTE_TEST_RX_DESC_MAX + RTE_TEST_TX_DESC_MAX +
> MAX_PKT_BURST +
> (nb_lcores * mb_mempool_cache);
>
It is a a little more complicated since some devices (like bnxt) allocate
multiple mbuf's per packet. Something like
nb_mbuf_per_pool = MAX_RX_QUEUES * (RTE_TEST_RX_DESC_MAX * MBUF_PER_RX +
MBUF_PER_Q)
+ MAX_TX_QUEUE * RTE_TEST_TX_DESC_MAX * MBUF_PER_TX
+ nb_lcores * MAX_PKT_BURST
+ nb_lcores * mb_mempool_cache
+ nb_lcores * PKTMBUF_POOL_RESERVED;
Ended up with
MBUF_PER_RX = 3
MBUF_PER_Q = 6
and when using jumbo
MBUF_PER_TX = MAX_MTU / MBUF_DATA_SIZE = 2
