[dpdk-dev] [PATCH 1/3] eal/x86: run-time dispatch over memcpy

[Stephen Hemminger]

I was referring to gcc multiversion

https://gcc.gnu.org/wiki/FunctionMultiVersioning


On Aug 30, 2017 6:24 PM, "Lu, Wenzhuo" <wenzhuo.lu at intel.com> wrote:

> Hi Stephen,
>
>
> > -----Original Message-----
> > From: Stephen Hemminger [mailto:stephen at networkplumber.org]
> > Sent: Thursday, August 31, 2017 2:01 AM
> > To: Li, Xiaoyun <xiaoyun.li at intel.com>
> > Cc: Richardson, Bruce <bruce.richardson at intel.com>; dev at dpdk.org; Lu,
> > Wenzhuo <wenzhuo.lu at intel.com>; Wang, Zhihong
> > <zhihong.wang at intel.com>; Zhang, Qi Z <qi.z.zhang at intel.com>
> > Subject: Re: [dpdk-dev] [PATCH 1/3] eal/x86: run-time dispatch over
> memcpy
> >
> > On Fri, 25 Aug 2017 10:06:11 +0800
> > Xiaoyun Li <xiaoyun.li at intel.com> wrote:
> >
> > > This patch dynamically selects functions of memcpy at run-time based
> > > on CPU flags that current machine supports. This patch uses function
> > > pointers which are bind to the relative functions at constrctor time.
> > > To make AVX512 instructions pass compilation, enable the switch in
> > > makefile.
> > >
> > > Signed-off-by: Xiaoyun Li <xiaoyun.li at intel.com>
> >
> > Recent versions of GCC also have better ways to handle this.
> I think the assumption of using the instructions is that we believe we can
> do better than the compiler. If it turns out not, maybe we need to change
> the instructions back to C. But it's another story.
>
>