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From: Florian Weimer <fweimer@redhat.com>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: Sajan Karumanchi <sajan.karumanchi@amd.com>,  GNU C Library
 <libc-alpha@sourceware.org>,  "Carlos O'Donell" <carlos@redhat.com>,
 "Mallappa, Premachandra" <premachandra.mallappa@amd.com>
Subject: Re: [PATCH 1/1] x86: Optimizing memcpy for AMD Zen architecture.
References: <20201022045005.17371-1-sajan.karumanchi@amd.com>
 <20201022045005.17371-2-sajan.karumanchi@amd.com>
 <CAMe9rOr8Zs7N2JPdo-COaY+z+5ujEm9u_e5EW_x=XFYgu1JHSg@mail.gmail.com>
Date: Wed, 28 Oct 2020 15:29:22 +0100
In-Reply-To: <CAMe9rOr8Zs7N2JPdo-COaY+z+5ujEm9u_e5EW_x=XFYgu1JHSg@mail.gmail.com>
 (H. J. Lu's message of "Wed, 28 Oct 2020 07:00:08 -0700")
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* H. J. Lu:

>>    if (cpu_features->data_cache_size !=3D 0)
>> -    data =3D cpu_features->data_cache_size;
>> +    {
>> +      if (data =3D=3D 0 || cpu_features->basic.kind !=3D arch_kind_amd)
>> +        data =3D cpu_features->data_cache_size;
>> +    }
>
> This looks wrong.  cpu_features->data_cache_size is set by
> GLIBC tunables:
>
> -- Tunable: glibc.cpu.x86_data_cache_size
>      The =E2=80=98glibc.cpu.x86_data_cache_size=E2=80=99 tunable allows t=
he user to set
>      data cache size in bytes for use in memory and string routines.
>
>      This tunable is specific to i386 and x86-64.
>
> Why is it ignored?

So we should revert those two hunks only?

Thanks,
Florian
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