svn commit: r300868 - head/tools/tools/ioat

Conrad Meyer cem at FreeBSD.org
Fri May 27 20:34:40 UTC 2016


On Fri, May 27, 2016 at 1:12 PM, Garrett Cooper <ngie at 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 limitation
>   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—the 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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