[dpdk-dev] [PATCH] net/i40e: Improve i40evf buffer cleanup in tx vector mode

[Bruce Richardson]

On Thu, Oct 05, 2017 at 03:11:11PM -0400, Roger B Melton wrote:
> ---
> 
> i40evf tx vector logic frees mbufs, but it does not remove the
> mbufs from software rings which leads to double frees.  This change
>  corrects that oversight.  We've validated this fix within our application.
> 

Hi Roger,

I'm a little concerned here by this driver fix, since if we are getting
double frees of mbufs there must be another bug somewhere in tracking
the free ring elements. Clearing the entries to NULL introduces extra
writes to the vector code path which will likely have a performance
impact, but also should be unnecessary, given proper tracking of the
ring status.

Can you provide us with some details as to how to reproduce the issue,
especially with a public sample app? I'd really like to look more into
why this is happening, and if other fixes may work.

Thanks,
/Bruce