LinuxDevices.com: Linux Scheduler Latency
Mar 22, 2002, 01:00 (6 Talkback[s])
(Other stories by Clark Williams)
"Since I'm primarily interested in embedded Linux and since most
embedded Linux systems are uniprocessor systems, my testing focused
exclusively on uniprocessors systems. I tested both patches on a
2.4.17 kernel under heavy load and while both patches significantly
reduced kernel latency, the testing shows that the low-latency
patches yielded the best reduction of Linux scheduler latency. The
low-latency patches had a maximum recorded latency of 1.3
milliseconds, while the preemption patches had a maximum latency of
45.2ms.
"A 2.4.17 kernel patched with a combination of both preemption
and low-latency patches yielded a maximum scheduler latency of 1.2
milliseconds, a slight improvement over the low-latency kernel.
However, running the low-latency patched kernel for greater than
twelve hours showed that there are still problem cases lurking,
with a maximum latency value of 215.2ms recorded. Running the
combined patch kernel for more than twelve hours showed a maximum
latency value of 1.5ms. This data seems to indicate that the best
solution for reducing Linux scheduler latency is to combine both
sets of patches..."
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