While playing with MySQL 5.7.5 on POWER8, I came across a rather interesting bug (74775 - and this is not the only one… I think I have a decent amount of auditing and patching to do now) which made me want to write a bit on memory barriers and the volatile keyword.
Memory barriers are hard.
Like, super hard. It’s the kind of thing that makes you curse hardware designers, probably because they’re not magically solving all your problems for you. Basically, as you get more CPU cores and each of them have caches, it gets more expensive to keep everything in sync. …[Read more...]