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Arm11 clock

Note: This was originally posted on 13th October 2008 at http://forums.arm.com

Hello,

Does anyone know if there is a timestamp clock in Arm? Something like the RDTSC in intel?
Or some other high frequency clock?
I need a clock to mesure performance of my linux kernel (and I use the RTC for something else).

Thanks everyone!

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0 Peter Harris over 12 years ago

Note: This was originally posted on 13th October 2008 at http://forums.arm.com

Linux is not ideal for hard real-time systems - even with the RT patch.

For an ARM11 processor worst case for something as large as Linux is exceedingly variable, and depends on things like whether the IRQ handler is in cache or not, and other memory system related activities.

Personal experience shows that interrupt latencies on Linux are in the order of 5000 cycles on an ARM1176 with a 2:1 core to bus memory ratio, and only a single layer of cache. A real platform might be significantly more cycles if the memory system is slow compared to the core.
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0 Peter Harris over 12 years ago

Note: This was originally posted on 13th October 2008 at http://forums.arm.com

Linux is not ideal for hard real-time systems - even with the RT patch.

For an ARM11 processor worst case for something as large as Linux is exceedingly variable, and depends on things like whether the IRQ handler is in cache or not, and other memory system related activities.

Personal experience shows that interrupt latencies on Linux are in the order of 5000 cycles on an ARM1176 with a 2:1 core to bus memory ratio, and only a single layer of cache. A real platform might be significantly more cycles if the memory system is slow compared to the core.
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