Re: Huge pages to be allocated based on number of mbufs

[Zoltan Kiss <zoltan.kiss@linaro.org>]

On 14/03/16 17:54, Saurabh Mishra wrote:
> Hi,
>
> We are planning to support virtio, vmxnet3, ixgbe, i40e, bxn2x and SR-IOV
> on some of them with DPDK.
>
> We have seen that even if we give correct number of mbufs given the number
> hugepages reserved, rte_eth_tx_queue_setup() may still fail with no enough
> memory (I saw this on i40evf but worked on virtio and vmxnet3).
>
> We like to know what's the recommended way to determine how many hugepages
> we should allocate given the number of mbufs such that queue setup APIs
> also don't fail.

I think you ran into a fragmentation problem. If you allocate the 
hugepages later on after startup, chances are they are fragmented in the 
memory. When you allocate a pool, DPDK needs a continuous area of memory 
on the hugepages.
You should allocate them through the kernel boot params so they'll be as 
continuous as possible.


>
> Since we will be running on low-end systems too we need to be careful about
> reserving hugepages.
>
> Thanks,
> /Saurabh
>