Hi,
just a curiosity, are there any 32-bits microcontrollers whose hardware architecture is designed or optimised for RTOS usage (perhaps high speed fewer instructions context switching)?
If so, which families/manufacturers?
And is the gain large or only small?
Thank you
Interesting, thank you Richard.
ARM Cortex M microprocessor family:
Every major firm has its own line of microcontrollers featuring such core: LPC from NXP, SAM from Atmel, STM32 from ST, and so on.
Thank you Xavier ! 
In my view, ARM Cortex M3 has been obsolescent for around 5 years. ARM Cortex M4 processors often cost less than M3, and many of them include floating point hardware. For higher performance there is M7, and for low cost applications where high performance is not needed, look for ARM Cortex M0+.
Thank you David !
@dc42,
One still real use of a M3 processor is the line of FPGAs that include a hard core CM3 with flash and ram and a suite of peripherals that can connect to the FPGA fabric. In many cases that processor is good enough.
Yes, if you need to add something else, there aren’t many discrete CM3’s that would be considered an optimal design point, as an CM4 will tend to overshadow it in every aspect. My guess any current CM3 product is really there to support legacy application needs.
It was an example of a microcontrollers tailored to be used along an operating system. Any Cortex-M processor has features towards be used with an OS.