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Date:   Thu, 24 Feb 2022 11:31:09 -0800
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Subject: Re: [RFC V2 0/5] Introduce AVX512 optimized crypto algorithms
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To:     Dave Hansen <dave.hansen@intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>
Cc:     Tony Luck <tony.luck@intel.com>,
        Asit K Mallick <asit.k.mallick@intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        "Chen, Tim C" <tim.c.chen@intel.com>,
        "Kleen, Andi" <andi.kleen@intel.com>, greg.b.tucker@intel.com,
        rajendrakumar.chinnaiyan@intel.com, tomasz.kantecki@intel.com,
        ryan.d.saffores@intel.com, Weiny Ira <ira.weiny@intel.com>,
        Eric Biggers <ebiggers@kernel.org>,
        Ard Biesheuvel <ardb@kernel.org>, X86 ML <x86@kernel.org>,
        anirudh.venkataramanan@intel.com
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From:   "Dey, Megha" <megha.dey@intel.com>
In-Reply-To: <0a10e16b-df77-9a7f-6964-8dc3e114b30b@intel.com>
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Hi all,

On 1/31/2022 11:18 AM, Dave Hansen wrote:
> On 1/31/22 10:43, Dey, Megha wrote:
>> With this implementation, we see a 1.5X improvement on ICX/ICL for 16KB
>> buffers compared to the existing kernel AES-GCM implementation that
>> works on 128-bit XMM registers.
> What is your best guess about how future-proof this implementation is?
>
> Will this be an ICL/ICX one-off?  Or, will implementations using 256-bit
> YMM registers continue to enjoy a frequency advantage over the 512-bit
> implementations for a long time?

Dave,

This would not be an ICL/ICX one off. For the foreseeable future, 
AVX512VL YMM implementations will enjoy a frequency advantage over 
AVX512L ZMM implementations.

Although, over time, ZMM and YMM will converge when it comes to performance.

Herbert/Andy,

Could you please let us know if this approach is a viable one and would 
be acceptable by the community?

Optimizing crypto algorithms using AVX512VL instructions gives a 1.5X 
performance improvement over existing AES-GCM algorithm in the 
kernel(using XMM registers) with no frequency drop.

Thanks,

Megha