Re: [lwip-devel] LwIP SMP Experience

[Simon Goldschmidt]

Joel Cunningham wrote:
> I have a couple products that run LwIP in an SMP environment with 
> CORE_LOCKING enabled. I haven’t done any SMP optimizations yet,

The performance problem I saw was not really only SMP related but could prefer 
high priority connections over low priority (at least for TX, RX is a bit 
trickier).
You (like the Minix and Hurd services) solved this by having multiple threads 
at socket level but not at pcb level...

> [..] we ran into issue with this because the event_callback in sockets.c 
> calls sys_sem_signal() while the spinlock was held

I'd rather fix this by saying we must not call sys_sem_signal() or 
sys_mbox_post() calls from SYS_ARCH_PROTECTed regions.
That could possibly be done by protecting the select_sb_list using an 
additional (global) mutex instead of SYS_ARCH_PROTECT.

Simon