It looks like the conversion from sbrk to mmap happened in 2009. https://www.openbsd.org/papers/eurobsdcon2009/otto-malloc.pdf https://www.openbsd.org/papers/e

It looks like the conversion from sbrk to mmap happened in 2009. https://www.openbsd.org/papers/eurobsdcon2009/otto-malloc.pdf https://www.openbsd.org/papers/eurobsdcon2009/otto-malloc.pd... https://undeadly.org/cgi?action=article;sid=20090106070242 https://undeadly.org/cgi?action=article;sid=20090106070242 https://news.ycombinator.com/item?id=3286254 https://news.ycombinator.com/item?id=3286254 https://web.archive.org/web/20111231094521/http://os-blog.com/how-openbsd-leverages-malloc-to-find-bugs/ https://web.archive.org/web/20111231094521/http://os-blog.co... General architecture: https://utcc.utoronto.ca/~cks/space/blog/unix/SbrkVersusMmap https://utcc.utoronto.ca/~cks/space/blog/unix/SbrkVersusMmap