Multicore requires OS rework, Windows architect advises

http://www.itworld.com/hardware/101580/multicore-requires-os-rework-windows-architect-advises

by abennett • 16 years ago

26 18 16 years ago

rpledge• 16 years ago

This will become even more relevant as core counts above 32 become common place. Sadly most programmers have a hard time dealing with more than 1 thread. I agree a new paradigm is needed to solve this problem.

Aegean4• 16 years ago

One good way to tackle is to use threads for hiding shared data. In a nutshell, instead of sharing variables between threads and protecting them by a lock, each thread has access to a portion of data, and they synchronously communicate. The result is easy, deterministic concurrency, and many cores may be used this way. One of the founding goals of the Go language is also based on this idea.

bad_user• 16 years ago

> instead of sharing variables between threads and protecting them by a lock, each thread has access to a portion of data, and they synchronously communicate

That's not enough.

If we are to believe Intel that we'll have processors with thousands of cores, then you have a new problem ... how are you going to keep all those cores busy (regardless of the actual number, from 32 to 20000)?

Another problem would be that you also want it to scale horizontally ... there's no reason why you'd want to know if another thread runs in the same process or on some other machine in China. All you care about is that you can spawn it, send a message to it and get some results.

Multiple techniques for concurrency will develop in parallel (which is a PITA since devs will need to have a lot of experience to choose), although I'm pretty sure that STM will be the most popular technique (although the handling of concurrency shouldn't be limited just to controlling access to RAM).

wheaties• 16 years ago

Thankfully people are pushing through STM and actor based parallelism. There's already an STM for Boost, Clojure, Erlang, and Scala to name a few.

jshen• 16 years ago

will there be an issue with stm when core counts get large enough that there are a lot of failed transactions? I'm not well read on stm, but intuitively this would seem to be an issue.

dkersten3• 16 years ago

And dataflow - a little bit, at least.

runT1ME2• 16 years ago

I'm really not sure Actors are the silver bullet. I write telcom software, and its just as easy to get a deadlock (ok maybe a little harder) using Actors than traditional locking.

Aegean4• 16 years ago

That's what my startup is about. Leveraging multiple cores using a hypervisor: http://www.l4dev.org

daeken• 16 years ago

Someone's actually commercializing L4? I've been hoping for that for a long time; good luck! While my own OS is very different (pure managed and all that jazz), I'll never forget the things I learned from L4, and it's great to see that someone's actually doing something real with it.

Aegean4• 16 years ago

I've been working on it for quite some time. Its nearly ready now, and it supports the quad core Cortex A9 - the latest intel rival mobile cpu.

impeachgod• 16 years ago

If it's not a secret, can you tell us more about your startup?

Aegean4• 16 years ago

Sure. It's a scrappy startup with a small team.

Company Name: B Labs

Company Founded: 2009

Age: 27

Product: B Labs develops a hypervisor/virtualization platform for high-end embedded systems.

Benefits:

- Multi-core processors of the future are utilized.

- Legacy applications ported over to multiple cpus.

- Security and separation of software components.

- Real-time and non real-time rich OS deployed on single platform.

http://www.b-labs.co.uk

Retric• 16 years ago

It was my understanding that this was how PS3's operate. The OS get's to use one of the more limited cores and the running program gets everything else.

aliston• 16 years ago

I'm not sure I agree with the "common" use case Probert is talking about. Sure, most people have multiple programs running at once, but a lot of the time the background processes are more or less running at idle or minimal CPU usage. So, I'm not sure that assigning a dedicated CPU per process would speed up things all that much...

xilun666• 16 years ago

Either this is bad journalism or the "architect" is really high. Because proposed re-architecture makes absolutely no sense.

The article starts with an obvious observation, being that scheduling (in its largest meaning) often is crap in real (Windows?) systems.

It concludes with complete meaningless bullshit where applications, now renamed, would have a dedicated CPU. What the point? Doing hard real-time? What does that even concretely means for "runtimes" of have a "dedicated" CPU (wich, given the complexity of modern architectures, would not really be in a strict fashion) and to do resource management thanks to metadata inserted by the compiler?

What is really needed is more effective ways for applications to sends tips to the kernel about what is going on, what should run at high priority, what should be cached, what should not be, and so over.

Forbidding some programs to use some cores because you have many makes little sense as a way to re-architecture an operating system. Because it already happens anyway on current designs (not really forbidden, but when you have few services consuming less than 1 percent of 1 core in the background, and/or running with extremely low priority they will be near to unnoticeable, and truly unnoticeable from the point of view of the user).

To get a responsive word processor no matter an anti-virus is loaded or not, a simple solution can work really well now; priorities of scheduling. Given that really background priorities are among the rare things that works fairly well under windows (like 10x better than with a vanilla Linux kernel), if the "architect" is experiencing random slow down of Word because of his "antivirus", its because his "antivirus" is total utter crap, not because a new "architecture" of OS is needed.

Multicore requires OS rework, Windows architect advises

Related Stories