Hi， Maxime:
> -----Original Message-----
> From: Maxime Coquelin [mailto:maxime.coque...@redhat.com]
> Sent: Friday, December 2, 2016 6:01 PM
> To: Yang, Zhiyong <zhiyong.y...@intel.com>; dev@dpdk.org
> Cc: yuanhan....@linux.intel.com; Richardson, Bruce
> <bruce.richard...@intel.com>; Ananyev, Konstantin
> <konstantin.anan...@intel.com>
> Subject: Re: [dpdk-dev] [PATCH 0/4] eal/common: introduce rte_memset
> and related test
>
> Hi Zhiyong,
>
> On 12/05/2016 09:26 AM, Zhiyong Yang wrote:
> > DPDK code has met performance drop badly in some case when calling
> > glibc function memset. Reference to discussions about memset in
> > http://dpdk.org/ml/archives/dev/2016-October/048628.html
> > It is necessary to introduce more high efficient function to fix it.
> > One important thing about rte_memset is that we can get clear control
> > on what instruction flow is used.
> >
> > This patchset introduces rte_memset to bring more high efficient
> > implementation, and will bring obvious perf improvement, especially
> > for small N bytes in the most application scenarios.
> >
> > Patch 1 implements rte_memset in the file rte_memset.h on IA platform
> > The file supports three types of instruction sets including sse & avx
> > (128bits), avx2(256bits) and avx512(512bits). rte_memset makes use of
> > vectorization and inline function to improve the perf on IA. In
> > addition, cache line and memory alignment are fully taken into
> consideration.
> >
> > Patch 2 implements functional autotest to validates the function
> > whether to work in a right way.
> >
> > Patch 3 implements performance autotest separately in cache and memory.
> >
> > Patch 4 Using rte_memset instead of copy_virtio_net_hdr can bring
> > 3%~4% performance improvements on IA platform from virtio/vhost
> > non-mergeable loopback testing.
> >
> > Zhiyong Yang (4):
> > eal/common: introduce rte_memset on IA platform
> > app/test: add functional autotest for rte_memset
> > app/test: add performance autotest for rte_memset
> > lib/librte_vhost: improve vhost perf using rte_memset
> >
> > app/test/Makefile | 3 +
> > app/test/test_memset.c | 158 +++++++++
> > app/test/test_memset_perf.c | 348
> > +++++++++++++++++++
> > doc/guides/rel_notes/release_17_02.rst | 11 +
> > .../common/include/arch/x86/rte_memset.h | 376
> +++++++++++++++++++++
> > lib/librte_eal/common/include/generic/rte_memset.h | 51 +++
> > lib/librte_vhost/virtio_net.c | 18 +-
> > 7 files changed, 958 insertions(+), 7 deletions(-) create mode
> > 100644 app/test/test_memset.c create mode 100644
> > app/test/test_memset_perf.c create mode 100644
> > lib/librte_eal/common/include/arch/x86/rte_memset.h
> > create mode 100644
> lib/librte_eal/common/include/generic/rte_memset.h
> >
>
> Thanks for the series, idea looks good to me.
>
> 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. :)
thanks
Zhiyong
> diff --git a/drivers/net/virtio/virtio_rxtx.c
> b/drivers/net/virtio/virtio_rxtx.c
> index 22d97a4..a5f70c4 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -287,7 +287,7 @@ virtqueue_enqueue_xmit(struct virtnet_tx *txvq,
> struct rte_mbuf *cookie,
> rte_pktmbuf_prepend(cookie, head_size);
> /* if offload disabled, it is not zeroed below, do it now */
> if (offload == 0)
> - memset(hdr, 0, head_size);
> + rte_memset(hdr, 0, head_size);
> } else if (use_indirect) {
> /* setup tx ring slot to point to indirect
> * descriptor list stored in reserved region.
>
> Cheers,
> Maxime
