[PATCH v2 1/1] sysdeps/x86: set Prefer_No_AVX512 for Hygon model 0x7

[Jiamei Xie]

Hi Lu,
  Thanks for your remind. I'll rebase and resubmit.

Regards
Jiamei Xie

> -----Original Message-----
> From: H.J. Lu <hjl.tools@gmail.com>
> Sent: 2025年11月10日 12:20
> To: Jiamei Xie <xiejiamei@hygon.cn>
> Cc: libc-alpha@sourceware.org; Jing Li <lijing@hygon.cn>
> Subject: Re: [PATCH v2 1/1] sysdeps/x86: set Prefer_No_AVX512 for Hygon
> model 0x7
> 
> On Fri, Nov 7, 2025 at 9:52 AM Jiamei Xie <xiejiamei@hygon.cn> wrote:
> >
> > Hi，
> >
> > Just a gentle ping on this patch. it has already received a Reviewed-by but
> has not been merged to master.
> > Please let me know if anything else is needed before the merge.
> 
> Your patch no longer applies.   Please rebase and resubmit.
> 
> > Thanks!
> > Jiamei
> >
> > > -----Original Message-----
> > > From: H.J. Lu <hjl.tools@gmail.com>
> > > Sent: 2025年10月16日 7:41
> > > To: Jiamei Xie <xiejiamei@hygon.cn>
> > > Cc: libc-alpha@sourceware.org; Jing Li <lijing@hygon.cn>
> > > Subject: Re: [PATCH v2 1/1] sysdeps/x86: set Prefer_No_AVX512 for
> > > Hygon model 0x7
> > >
> > > On Tue, Oct 14, 2025 at 5:22 PM Jiamei Xie <xiejiamei@hygon.cn> wrote:
> > > >
> > > > Benchmarks on Hygon hardware show that EVEX often outperforms
> AVX-512.
> > > > To reflect this, enable the Prefer_No_AVX512 flag for model 0x7 so
> > > > that the ifunc selector will favor EVEX paths over AVX-512 for that model.
> > > >
> > > > Signed-off-by: Li jing <lijing@hygon.cn>
> > > > Signed-off-by: Xie jiamei <xiejiamei@hygon.cn>
> > > > ---
> > > >  sysdeps/x86/cpu-features.c | 5 +++++
> > > >  1 file changed, 5 insertions(+)
> > > >
> > > > diff --git a/sysdeps/x86/cpu-features.c
> > > > b/sysdeps/x86/cpu-features.c index b67ef541dd..4ec4c43718 100644
> > > > --- a/sysdeps/x86/cpu-features.c
> > > > +++ b/sysdeps/x86/cpu-features.c
> > > > @@ -1123,6 +1123,11 @@ disable_tsx:
> > > >         hardware.  */
> > > >
> cpu_features->preferred[index_arch_Avoid_Non_Temporal_Memset]
> > > >             &= ~bit_arch_Avoid_Non_Temporal_Memset;
> > > > +
> > > > +      /* On Hygon model 0x7, benchmarks show EVEX often beats
> > > AVX-512 */
> > > > +      if (model == 0x7)
> > > > +        cpu_features->preferred[index_arch_Prefer_No_AVX512]
> > > > +          |= bit_arch_Prefer_No_AVX512;
> > > >      }
> > > >    else
> > > >      {
> > > > --
> > > > 2.17.1
> > > >
> > > >
> > >
> > > LGTM.
> > >
> > > Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
> > >
> > > Thanks.
> > >
> > > --
> > > H.J.
> >
> 
> 
> --
> H.J.