Linked by David Adams on Fri 18th Apr 2008 17:34 UTC, submitted by Rahul
Linux Lennart Poettering of Red Hat, PulseAudio maintainer has blogged in detail about the impact of Real-Time Group scheduling in 2.6.25 kernel. The Real time patches come from -rt patchset maintained by Ingo Molnar of Red Hat which aims to make Linux the first general purpose operating system with hard real time features.
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HARD real time? I don't think so
by Bahadir on Fri 18th Apr 2008 21:31 UTC
Bahadir
Member since:
2007-05-19

Nowhere in the article I have seen the phrase "hard real-time" please let's not abuse phrases. Hard real-time means deadlines are "guaranteed" to be met at any circumstance and Linux is not capable of doing this below the microsecond level. In fact its not just Linux but the combination of hardware and the OS that needs to have this support, in order to achieve hard real-time. For example unavoidable hardware exceptions with higher priority would give enough non-determinism to reduce your system to "soft real-time".

I would say merely the article's summary is, "Linux can control real-time tasks (implying deadline-sensitive) with higher precision."

Reply Score: 6

Rahul Member since:
2005-07-06

Take a look at

http://kerneltrap.org/node/11752
http://rt.wiki.kernel.org/

Hard real time cannot be achieved with the vanilla kernel but this patchset can enable that. Vendors are already shipping products based on this.

http://www.redhat.com/mrg/

Reply Parent Score: 5

Bahadir Member since:
2007-05-19

Yes all those links show that linux can work with *soft* real-time capability. *Hard* real-time is different as previously mentioned.

This is also why for instance linux is usually multiplexed with another RTOS for such delicate operations (e.g. modem communication on mobile phones).

Reply Parent Score: 5