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From:   David Laight <David.Laight@ACULAB.COM>
To:     'Andi Kleen' <ak@linux.intel.com>, Michal Hocko <mhocko@kernel.org>
CC:     "Kirill A. Shutemov" <kirill@shutemov.name>,
        Cannon Matthews <cannonmatthews@google.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        "Andrew Morton" <akpm@linux-foundation.org>,
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        David Rientjes <rientjes@google.com>,
        Greg Thelen <gthelen@google.com>,
        Salman Qazi <sqazi@google.com>,
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>
Subject: RE: [PATCH] mm: clear 1G pages with streaming stores on x86
Thread-Topic: [PATCH] mm: clear 1G pages with streaming stores on x86
Thread-Index: AQHV9ijM3XjXd8DH7k20GvQVG1posahDf+RQ
Date:   Wed, 11 Mar 2020 15:07:07 +0000
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From: Andi Kleen
> Sent: 09 March 2020 15:39
...
> There's a cautious tale of the old crappy RAID5 XOR assembler functions which
> were optimized a long time ago for the Pentium1, and stayed around,
> even though the compiler could actually do a better job.

Or the amd64 asm loop for doing the IP checksum.
I doubt it was even the fastest version when it was written.
A whole set of Intel cpus can run twice as fast as that version
with less loop unrolling (and associated code for 'odd' lengths).

	David

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