I was big into OS dev when Mach was coming around but I was a newbie.  I read all the Mach papers with stars in my eyes, it all sounded so good.  I wasn&#x27;t alone in getting drawn in by the research papers.<p>I went to Sun and learned how a kernel could work and could perform and the allure of Mach, for me, started to wane.  Reading the mach code made it worse, especially compared to the Sun code.<p>All these years later, I remain underwhelmed.  Linux has a nicer VM system, performs better, and is more readable.  Not Sun level readable by any stretch, but better than my memory of mach (which, to be fair, is in the distant past).<p>If someone can point to actual real world data that shows Mach to be better performing on the same hardware I&#x27;d be interested in seeing that, I tend to think that&#x27;s not possible.<p>If you want to see what a real microkernel done right looks like, go look at QNX before they added the POSIX conformance.  You have 4-5 people logged into an 80286 doing work.  Very, very light weight and well done.  They were the only guys that understood what the &quot;micro&quot; in microkernel meant.  I remember Dan Hildebrandt telling me that the microkernel easily fit in a 4K instruction cache (it pretty much had to, it didn&#x27;t do much so you needed some space for whatever it was dispatching).