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Date: Tue, 24 Jul 2018 09:29:15 +0200
From: Olivier Matz <olivier.matz@6wind.com>
To: "Wiles, Keith" <keith.wiles@intel.com>
Cc: Morten =?iso-8859-1?Q?Br=F8rup?= <mb@smartsharesystems.com>,
 Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>,
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Subject: Re: [dpdk-dev] rte_mbuf library likely()/unlikely()
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Hi,

On Mon, Jul 23, 2018 at 10:40:03PM +0000, Wiles, Keith wrote:
> 
> 
> > On Jul 23, 2018, at 2:09 PM, Morten Brørup <mb@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.

I agree we should be driven by performance improvements.

I remember a discussion with Bruce on the ML saying that hardware branch
predictors generally do a good job.

Thanks,
Olivier