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Date:      Thu, 30 Jan 2020 17:49:21 +0000
From:      bugzilla-noreply@freebsd.org
To:        geom@FreeBSD.org
Subject:   [Bug 242747] geli: AMD Epyc+GELI not using Hardware AES
Message-ID:  <bug-242747-14739-JkzUPwAgvB@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-242747-14739@https.bugs.freebsd.org/bugzilla/>
References:  <bug-242747-14739@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D242747

--- Comment #11 from Conrad Meyer <cem@freebsd.org> ---
Yeah, I suspect NCPU threads per disk across 8 disks is not really a great
default!  geli's ncpu default is probably reasonable for single-disk laptop=
s,
but doesn't factor in larger arrays.  threads=3D2 x 8 disks gets you to 16,=
 or
the number of real cores.  IIRC Epyc has only 128-bit wide vector units
internally, but I don't see how that would affect aesni(4); AES itself is a
128-bit cipher, and the aesni(4) driver only uses SSE intrinsics, which act=
 on
128-bit vectors.  It may simply have fewer vector units and attempting to u=
se
32 of them at the same time contests for shared resources.

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