[dpdk-dev] [PATCH 0/4] eal/common: introduce rte_memset and related test

Yang, Zhiyong zhiyong.yang at intel.com
Wed Dec 7 10:43:06 CET 2016


Hi, yuanhan:

> -----Original Message-----
> From: Yuanhan Liu [mailto:yuanhan.liu at linux.intel.com]
> Sent: Wednesday, December 7, 2016 5:38 PM
> To: Yang, Zhiyong <zhiyong.yang at intel.com>
> Cc: Maxime Coquelin <maxime.coquelin at redhat.com>; dev at dpdk.org;
> Richardson, Bruce <bruce.richardson at intel.com>; Ananyev, Konstantin
> <konstantin.ananyev at intel.com>; Pierre Pfister (ppfister)
> <ppfister at cisco.com>
> Subject: Re: [dpdk-dev] [PATCH 0/4] eal/common: introduce rte_memset
> and related test
> 
> On Wed, Dec 07, 2016 at 09:28:17AM +0000, Yang, Zhiyong wrote:
> > > >> Wouldn't be worth to also use rte_memset in Virtio PMD (not
> > > >> compiled/tested)? :
> > > >>
> > > >
> > > > I think  rte_memset  maybe can bring some benefit here,  but , I'm
> > > > not clear how to enter the branch and test it. :)
> > >
> > > Indeed, you will need Pierre's patch:
> > > [dpdk-dev] [PATCH] virtio: tx with can_push when VERSION_1 is set
> 
> I will apply it shortly.
> 
> > > Thanks,
> > > Maxime
> > > >
> > Thank you Maxime.
> > I can see a little, but not obviously  performance improvement here.
> 
> Are you you have run into that code piece? FYI, you have to enable virtio 1.0
> explicitly, which is disabled by deafault.

Yes. I use the patch from Pierre and set offload  = 0 ; 
Thanks
Zhiyong

> 
> > You know, memset(hdr, 0, head_size); only consumes  fewer cycles for
> virtio pmd.
> > head_size only  10 or 12 bytes.
> > I optimize rte_memset perf further for N=8~15 bytes.
> > The main purpose of Introducing rte_memset is that we can use it to
> > avoid perf drop issue instead of glibc memset on some platform, I think.
> 
> For this case (as well as the 4th patch), it's more about making sure
> rte_memset is inlined.
> 
> 	--yliu


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