Linked by Thom Holwerda on Fri 25th Sep 2009 23:12 UTC, submitted by Still Lynn
Microsoft Most of us are probably aware of Singularity, a research operating system out of Microsoft Research which explored a number of new ideas, which is available as open source software. Singularity isn't the only research OS out of Microsoft; they recently released the first snapshot of a new operating system, called Barrelfish. It introduces the concept of the multikernel, which treats a multicore system as a network of independent cores, using ideas from distributed systems.
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RE: Comment by kaiwai
by kjmph on Sat 26th Sep 2009 22:42 UTC in reply to "Comment by kaiwai"
kjmph
Member since:
2009-07-17

Yes, good points. I would presume that this model would only take down applications that were currently running on the failed core. However, you would have to deal with messages in flight to the running core, so there would be unknown state to clean up. I bet you could easily cycle/reset the core into a known state. So, greater up-time in the long run.

As far as overhead is concerned, they say that native IPC was 420 cycles and the similar message passing implementation cost 757 cycles. That's 151ns vs 270ns on the 2.8GHz chips they were testing on. However, by breaking the current synchronous approach and using a user RPC mechanism they dropped the message passing to 450cycles on die, and 532cycles one hop. With two hops only costing tens of cycles more. Which is really starting to become negligible. So, it does cost, but where they excelled was multi-core shared memory updates. But, to get back to your comments, that really is not general purpose computing as of today, as most applications on my Linux box are single threaded. Of the few apps that aren't single threaded, ffmpeg and Id's Doom3 engine, they are most likely aren't synchronizing shared memory updates, rather I think they would isolate memory access to certain threads and pass commands around via a dispatcher thread. So, this is a pretty specific type of applications that excel on Barrelfish. I think they are targeting Google's MapReduce and Microsoft's Dryad.

Finally, it's important to notice that HW is moving to a message passing type architecture as well. AMD had implemented HyperTransport and Intel now has the QuickPath Interconnect. So, in Barrelfish, the implementation of the message passing on AMD's cpus is based on cache lines being routed via HT. In other words, hardware accelerated message passing. They isolated the transport mechanism from the message passing API, so I believe they could swap in different accelerated transport implementations depending on the architecture it's currently running on.

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