Hacker News Reader

Comment by rbanffy | Hacker News Reader

The performance issues reported suggest the software treats all cores as equal and, with that, when you start multiple processes or threads that need to complete for something to happen, you'll end up waiting for the slowest one. That might be bearable on symmetrical multi-core but is an issue with asymmetrical chips.

Does anyone knows whether Linux can migrate processes from slow cores to fast ones if the fast one is idling?

View on HN

I've been wondering this too. To my knowledge I don't know of any language/framework threading implementations that let you do certain functions in a "fast core thread" and others in a "slow core thread".

I'm guessing this means the kernel is making the decisions, which sucks for application developers.

How does Android (Linux) handle big.LITTLE chipsets? From what I understand they’ve had this process for years so there must be some software they’re using to handle what process goes to what core. Is that not something they’ve upstreamed to the main Linux codebase?

Depends on the phone. Most 2015-2019 Qualcomm phones use niceness to determine CPU allocation, whereas Android 10 has more complete cgroup support where different groups are assigned to different cores and the APIs categorize tasks / threads / processes by what they are doing into different execution profiles. Pre 10 had some fixed cgroups available but it wasn't as comprehensive.

Reply on news.ycombinator.com