[GitHub] [incubator-nuttx] v01d commented on issue #3599: Syslog thread-safety

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

v01d commented on issue #3599:
URL: https://github.com/apache/incubator-nuttx/issues/3599#issuecomment-825628425


   > @fjpanag just to be clear interrupts can not wait on a semaphore [see](https://github.com/apache/incubator-nuttx/blob/master/sched/semaphore/sem_wait.c#L78)
   
   That is the reason I think the current design is based around printing each character as it can be done without locking when using a circular buffer. But this is really inefficient for things like UART.
   
   I think the way to go would be to always use an interrupt buffer and use a work queue for logging to "slow channels". On the other hand, since logging to RAMLOG is instantaneous and already provides buffer, a semaphore could be used directly. 
   The issue about breaking on buffer boundaries maybe can be done by flushing in separate lines. If the output is indeed a very large line, it most likely should be split in various lines


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