Date: Fri, 27 May 2016 13:51:15 -0700 From: "Ngie Cooper (yaneurabeya)" <yaneurabeya@gmail.com> To: cem@FreeBSD.org Cc: Garrett Cooper <ngie@freebsd.org>, 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: <2F93033E-D202-4A0A-8555-76ED789D4080@gmail.com> In-Reply-To: <CAG6CVpUt425z_YyTb7E7TGDkTuZFpGDjz6N3JRg3Ksq6K6-ZuQ@mail.gmail.com> References: <201605272012.u4RKCWCI035708@repo.freebsd.org> <CAG6CVpUt425z_YyTb7E7TGDkTuZFpGDjz6N3JRg3Ksq6K6-ZuQ@mail.gmail.com>
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[-- Attachment #1 --] > On May 27, 2016, at 13:34, Conrad Meyer <cem@FreeBSD.org> wrote: > > 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 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 [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Comment: GPGTools - https://gpgtools.org iQIcBAEBCgAGBQJXSLNDAAoJEPWDqSZpMIYVubYP/RddAOw+DSkQGM5nZqFMK9nK fss62CtKxndy0YWJ/LMTSuFovDMqFDZ+QRr74DDrFXAAW1aS7+yDaWJK6lGXTJs5 I9Q9bXHMm4NmJpBEWxmA7PMwy1nKac+CDBXqOKWAv1Nr/FgaPXoxYHuRUYpW15pc YO2hKByGU3aP39+LeLcgtXSPzw3k96b0dpQQTEgciqq76UxTok01OsKANucYQ8Uw bt/9lRu2U26deXjj1wXmvr6CtM0+hrhi0HZ2Kz4kRRVSijBFm7CLmjAqvXePA/cI JyhDYy4CSjZrC4f1dn40KoRY2mwLDqk6RTSwnXRGAb3r7qEsbBkQ6JwHPqSUAw1t MHWO+H+dIjXTSxXSz2+3vDR9Jjvt/y5V0QLxRU8P+tb0s/HwgX2YHWPT4NFHzoVY TojtrwVs5z7Jo7Boh6l2xjPKCUClFpD3i/ODT/AYpg53bXbGyVQK4RgCuuYF6rZd HHHzIpxgBEToR70LIWKjRrGa04bhavGV9KGXtX8WUAkR44A9nFDFulbuQJeiPZan DOg76eStxfFi5QZ6oXKwzpxXd1LD9I5KN3ie5XfeqVV1/s+97kQALuWyuZ+hZJkF SwV/BtEj40aePOYfBcJK6xh1POVQCZ1Is9Cm+eBqw3w64LrD63eIGexU5aZUmlV1 Lh9CYFtyi8VWgyE0V50h =O5xs -----END PGP SIGNATURE-----
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