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Kernel 2.6 Real-Time Benchmarks
An anonymous reader writes "This whitepaper at LinuxDevices.com includes benchmarks comparing the real-time performance of the vers. 2.4 and 2.6 linux kernels, based on LynuxWorks' BlueCat Linux 5.0 beta. The graphs compare the results for average and worst-case measurements of both interrupt response and task switch performance for the two kernels, running on a 1GHz Pentium III under relatively heavy load. Check it out -- there's an enormous improvement. The article also includes a rundown of other features of the new kernel that seem likely to be welcomed by embedded developers."
LKML verified it and I've experienced it personally -- TCQ on IBM Deathstar drives (mine were 60G, the LKML was 120G IIRC) can cause massive fs corruption.
Apparently a queue depth of 8 (the default it seems) is the specific culprit. LKML seems to say that TCQ of 32 works but I've turned it off entirely now.
It's marked experimental for a reason. :-)
Taken from the article you reference:
SO... they compared a RTOS with an (admitedly) non-realtime OS? I'm not surprised at the results.
RedHat markets ELDS as an OS for embedded systems. Not all embedded systems require realtime performance. Heck, even systems that require realtime performance don't always require the level of performance that QNX can deliver. There's a large number of embedded systems for which even plain Linux without any performance enhancements is a good choice.
If you're really looking for a version of Linux that supports hard real time requirements, take a look at something other than ELDS - <shameless plug> TimeSys Linux, for example </shameless plug>
(yes, I am a TImeSys employee)."Great men are not always wise: neither do the aged understand judgement." Job 32:9
It schedules tasks, handles input/output with hardware, allocates storage and memory, manages processes... it's an operating system. Now, it may be more precise to say "Red Hat Linux" or "GNU/Linux", but that doesn't mean that Linux isn't an operating system.
"The price of freedom is eternal vigilance." - Thomas Jefferson
It seems you need "a system means that performs its functions and responds to external, asynchronous events within a specified amount of time". In other words, a real-time OS. Neither Windows nor Linux are real-time OS. There is some patches that aims at making Linux more real-time.
You can use Tron too.
No GNU has been Hurd during the making of this comment.
The Linux kernel was never intented to compete with QNX or any other realtime operating system.
Try RTAI. It's a patch to allow hard realtime performance on GNU/Linux systems.