"4. sort the time taken by: CPU register read, disk seek, context switch, system memory read.
Me: CPU register read, system memory read, context switch, disk seek.
Recruiter: right."
This is the exact question I got in a phone screen (although mine included CPU caches so was actually harder) for the lowest level SRE position at Google. That and the obvious lack of knowledge of their interviewer, who I'd expect to know these answers inside and out, point to Google lowering the bar extensively not only on their interviewing practices (where it certainly was never high as in quality) but on the actual quality of their hires. Any SRE could be Director of Engineering at Google, apparently, going by this test. I'd say that equates to not having a bar at all.