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Date:      Fri, 27 May 2016 13:34:32 -0700
From:      Conrad Meyer <cem@FreeBSD.org>
To:        Garrett Cooper <ngie@freebsd.org>
Cc:        src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org,  svn-src-head@freebsd.org
Subject:   Re: svn commit: r300868 - head/tools/tools/ioat
Message-ID:  <CAG6CVpUt425z_YyTb7E7TGDkTuZFpGDjz6N3JRg3Ksq6K6-ZuQ@mail.gmail.com>
In-Reply-To: <201605272012.u4RKCWCI035708@repo.freebsd.org>
References:  <201605272012.u4RKCWCI035708@repo.freebsd.org>

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On Fri, May 27, 2016 at 1:12 PM, Garrett Cooper <ngie@freebsd.org> wrote:
> Author: ngie
> Date: Fri May 27 20:12:32 2016
> New Revision: 300868
> URL: https://svnweb.freebsd.org/changeset/base/300868
>
> Log:
>   Remove note about bogus chain-len maximum
>
>   There's no current limit on chain-len with Broadwell DE chips; it isn't
>   enforced in software, and there doesn't appear to be a hardware limitat=
ion
>   either on the Intel Xeon D-1527 (Broadwell-DE) chip.

Hi Ngie,

The note isn't bogus, it's just not what you think it is=E2=80=94the limit =
is
in the ioat_test code, not a limit of the hardware.

Before this commit which documented it (r289733), the limit *was* 4.
However, in the same commit I bumped the limit up to 128
(IOAT_MAX_BUFS / 2).  (I suspect I wrote the documentation first,
before deciding to raise the limit.)

So the current limit is 128, and should be documented.

Thanks,
Conrad



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