> On Jul 23, 2018, at 2:09 PM, Morten Brørup <m...@smartsharesystems.com> wrote: > > I haven't performance tested, but they are compiler branch prediction hints > pointing out the most likely execution path, so I expect them to have a > positive effect.
We really need to make sure this provides any performance improvement and that means it needs to be tested on a number of systems. Can you please do some performance testing or see if we can get the guys doing DPDK performance testing to first give this a try? This area is very sensitive to tweaking. > > E.g. the first comparison in __rte_pktmbuf_read() is very unlikely to be true > - it would mean that the application is trying to read data beyond the packet. > > Please also refer to: > https://cellperformance.beyond3d.com/articles/2006/04/branch-patterns-using-gcc.html > > >> -----Original Message----- >> From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Honnappa Nagarahalli >> Sent: Monday, July 23, 2018 7:52 PM >> To: Morten Brørup; Olivier Matz >> Cc: dev@dpdk.org >> Subject: Re: [dpdk-dev] rte_mbuf library likely()/unlikely() >> >> Do you see any performance improvements with these changes? >> >> -----Original Message----- >> From: dev <dev-boun...@dpdk.org> On Behalf Of Morten Brørup >> Sent: Monday, July 23, 2018 8:54 AM >> To: Olivier Matz <olivier.m...@6wind.com> >> Cc: dev@dpdk.org >> Subject: [dpdk-dev] rte_mbuf library likely()/unlikely() >> >> Hi Olivier, >> >> >> >> I noticed that __rte_pktmbuf_read() could do with an unlikely(), so I went >> through the entire library. Here are my suggested modifications. >> Regards, Keith
