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It's worth pointing out that the FreeBSD implementation (on AMD64) only promotes 4kB pages to 2MB pages and doesn't transparently promote to 1GB pages.

Given alc@ was an author on the paper (and the paper's FreeBSD 4.x implementation supported multiple superpage sizes), I'm not really sure why FreeBSD's pmap doesn't have support for 1GB page promotions.



F5/LineRate did it but it got NACKed in a fairly underhanded and unfortunate way on the mailing lists :/ https://github.com/Seb-LineRate/freebsd/commits/seb/stable-1...


That patch set does not implement transparent creation of 1GB mappings. It also contains dubious things like this, which make me think the branch was a WIP: https://github.com/Seb-LineRate/freebsd/commit/66a8d3474d410...

The only mailing list thread I see regarding this is here, and it doesn't seem particularly underhanded to me: https://lists.freebsd.org/pipermail/freebsd-hackers/2014-Nov...


All the technical critique seems fair but it seemed like they (both as an individual and as a company) were a first time contributor and no outreach was really done to pull them in further. I guess LineRate imploded within F5 so there could have been structural problems inside there prevented them from doing a fully baked contribution anyway.


Can you clarify what you mean by "underhanded and unfortunate way?" The thread I can see on freebsd-hackers@ had a little feedback, including some very valid critiques (the code was developed against 9.x, then ported to 10.x without testing, at a time when 11 was CURRENT) and the original author just didn't follow up at all:

https://lists.freebsd.org/pipermail/freebsd-hackers/2014-Nov...

But maybe I'm missing something?

See also: https://lists.freebsd.org/pipermail/freebsd-hackers/2013-Sep...




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