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Date: Wed, 7 Dec 2016 17:37:42 +0800
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
To: "Yang, Zhiyong" <zhiyong.yang@intel.com>
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Subject: Re: [dpdk-dev] [PATCH 0/4] eal/common: introduce rte_memset and
 related test
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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.

> 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