issue 1:
sys_arch_sem_wait() is supposed to return an elapsed time in ms, what could
happen given a > 1 kHz calling rate for high throughput systems is that it
might always returns 0 ms. This is a problem for systems which compute the
elapsed time from a high precision clock source.
This is what is currently happening in the unix port in sys_arch_sem_wait():
start time -> 1000000000; // ns
-- less than a ms before an event arrive --
end time -> 1000xxxxxx; // ns
return value -> (end time - start time)/1000000 -> 0
The return value is used to reduce the next timer interval, if
sys_arch_sem_wait() always return 0 no more timers are fired anymore
issue 2:
The current timer implementation for !NO_SYS targets only count elapsed
time while -waiting- for semaphore and doesn't count at all the time
spent by the stack to process packets. For CPU bound traffic patterns no
more timers are fired anymore.
Both are serious design issues which cannot be easily fixed without reworking
everything. This patch uses the properly implemented timers for NO_SYS targets
for !NO_SYS targets and merge them both into one single timers implementation.
lwip/src/core/timers.c: In function ‘sys_check_timeouts’:
lwip/src/core/timers.c:328:5: error: "PBUF_POOL_FREE_OOSEQ" is not defined [-Werror=undef]
#if PBUF_POOL_FREE_OOSEQ
Fix it by declaring an empty PBUF_CHECK_FREE_OOSEQ() function if feature is
not enabled.
ip_addr_t is used for all generic IP addresses for the API, ip(4/6)_addr_t are only used internally or when initializing netifs or when calling version-related functions
although timeouts are relative to timeouts_last_time (transitively by
addition to the time values of their predecessors, if there are any),
sys_timeout does not compensate for that; as a result, timeouts fire too
early unless invoked from within a timeout handler (when
timeouts_last_time == now).
