[PATCH 5/6] net: add smaller IPv4 cksum function for simple cases

[Bruce Richardson]

On Thu, Oct 17, 2024 at 09:24:37AM -0700, Stephen Hemminger wrote:
> On Thu, 17 Oct 2024 15:22:12 +0100
> Bruce Richardson <bruce.richardson at intel.com> wrote:
> 
> > There are multiple instances in the DPDK app folder where we set up an
> > IP header and then compute the checksum field by direct addition of
> > nine uint16_t values in the header (20 bytes less the cksum field).
> > The existing rte_ip.h checksum function is more general than necessary
> > here and requires that the checksum field is already set to zero -
> > rather than having it skipped.
> > 
> > Fix the code duplication present in the apps by creating a new
> > rte_ipv4_cksum_simple function - taking the code from the existing
> > testpmd icmpecho.c file - and using that in app/test, testpmd and
> > testeventdev.
> > 
> > Within that new function, we can adjust slightly how the typecasting to
> > uint16_t is done, and thereby ensure that the app can all be compiled
> > without -Wno-address-of-packed-member compiler flag.
> > 
> > Signed-off-by: Bruce Richardson <bruce.richardson at intel.com>
> 
> DPDK should use the same optimization as FreeBSD and Linux
> and use 32 bit add's here.
> 

Yep. And if we get this patch applied, there is only one place to optimize, not
a dozen! :-)