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

[Ngie Cooper (yaneurabeya)]

> On May 27, 2016, at 13:34, Conrad Meyer <cem at FreeBSD.org> wrote:
> 
> 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.

Ah… that makes sense. Would it be a better idea to make this limit into a readonly sysctl in ioat_test(4), along with the other limits? If so, I’ll put that out for CR.
Thanks,
-Ngie
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