This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH] Use AVX_Fast_Unaligned_Load from Zen onwards.
- From: Alexey Tourbin <alexey dot tourbin at gmail dot com>
- To: Amit Pawar <Amit dot Pawar at amd dot com>
- Cc: libc-alpha at sourceware dot org
- Date: Sun, 30 Sep 2018 16:14:21 +0300
- Subject: Re: [PATCH] Use AVX_Fast_Unaligned_Load from Zen onwards.
- References: <20180930125445.GA1525@celery.localdomain>
On Sun, Sep 30, 2018 at 03:54:45PM +0300, Alexey Tourbin wrote:
> On Fri, Jul 06, 2018 at 09:55:36AM -0400, Amit Pawar wrote:
> > From Zen onwards this will be enabled. It was disabled for the
> > Excavator case and will remain disabled.
>
> Wasn't it also disabled for Bulldozer and older models?
But Excavator is the only one with AVX2 support, I see now.
> > --- a/sysdeps/x86/cpu-features.c
> > +++ b/sysdeps/x86/cpu-features.c
> > @@ -78,8 +78,15 @@ get_common_indeces (struct cpu_features *cpu_features,
> > /* The following features depend on AVX being usable. */
> > /* Determine if AVX2 is usable. */
> > if (CPU_FEATURES_CPU_P (cpu_features, AVX2))
> > + {
> > cpu_features->feature[index_arch_AVX2_Usable]
> > |= bit_arch_AVX2_Usable;
> > +
> > + /* Unaligned load with 256-bit AVX registers are faster on
> > + Intel/AMD processors with AVX2. */
> > + cpu_features->feature[index_arch_AVX_Fast_Unaligned_Load]
> > + |= bit_arch_AVX_Fast_Unaligned_Load;
> > + }