Can't tell if you're agreeing or disagreeing with this, but what I was trying to say is that full GCs happen (even when generational lets you delay them), thrash your caches to trace all live pointers in your heap, and still run faster on multiple cores. That seems to be in tension with the blog post's suggestion that you need locality for parallelism.

Many recent GCs don't actually try to use all your cores because they run concurrent with your app and want to leave a lot of capacity for it, but Go 1.4's GC (the last non-concurrent version) used all the cores it could, and V8's Orinico does in some phases too.