[GitHub] [incubator-nuttx] patacongo commented on issue #1133: Improved Back-to-Back Interrupt Performance

[GitBox <gi...@apache.org>]

patacongo commented on issue #1133:
URL: https://github.com/apache/incubator-nuttx/issues/1133#issuecomment-634279614


   Here is another though of a way to improve ARMv7-M  interrupt performance.  This would improve interrupt performance be avoiding saving some registers unnecessarily.
   
   Here is an overview of ARMv7-M interrupt interrupt processing:
   
   1.  On interrupt, hardware saves some state and all C volatile registers.
   2.  _Save static registers_ in the interrupt handler
   3. Dispatch interrupt via arm_doirq();
   4. if an context switch occurs, restore all registers of new thread and return from interrupt
   5. Restore only the minimum register set and return from interrupt
   
   That could be improved as follows:
   
   1.  On interrupt, hardware saves some state and all C volatile registers.
   2. Dispatch interrupt via arm_doirq();
   3. if an context switch occurs:  (a) _save static registers_ then (b) restore all registers of the new thread and return from interrupt
   5. Restore only the minimum register set and return from interrupt
   


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