What about threads?

Posted Apr 22, 2004 20:36 UTC (Thu) by stuart2048 (guest, #6241)
Parent article: Scheduling domains

This balancing technique, as it is described here, seems to talk about scheduling processes. But in my notion of the OS world, processes don't actually run -- threads do. So isn't this more about thread scheduling than process scheduling? Granted, I have never poked around any of the scheduler or process management code in Linux, so I could be way off...

I would be interested to learn how this scheduler deals with processes with multiple busy threads on, say, NUMA or SMP hardware.

Thanks for the great article, and keep those cheesy diagrams coming!

--Stuart

What about threads?

Posted Apr 23, 2004 0:32 UTC (Fri) by hmh (subscriber, #3838) [Link]

A thread and a process are usually about the same thing in Linux.

What about threads?

Posted Apr 23, 2004 21:54 UTC (Fri) by giraffedata (guest, #1954) [Link]

We're actually in a thread/process terminology crisis in Linux. Various people have various ideas about what we should mean by "thread," "process," "task," and "thread group."

It's bad right now because the thread/process model in Linux only recently changed, making what was once a pretty well agreed upon terminology less useful.

So the article is about Linux processes in the old terminology, the terminology you will still see in most of the comments in the Linux code. In that terminology, a "process" is in fact the most basic unit of scheduling known to the Linux kernel, and is what implements a thread in the POSIX thread model. It is alternatively called a "thread" and a "task."