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

["Yang, Zhiyong" <zhiyong.yang@intel.com>]

Hi， Maxime:

> -----Original Message-----
> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com]
> Sent: Friday, December 2, 2016 6:01 PM
> To: Yang, Zhiyong <zhiyong.yang@intel.com>; dev@dpdk.org
> Cc: yuanhan.liu@linux.intel.com; Richardson, Bruce
> <bruce.richardson@intel.com>; Ananyev, Konstantin
> <konstantin.ananyev@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