On 05/20/2009 07:31 PM, Andrei Pelinescu-Onciul wrote:
On May 20, 2009 at 19:24, Daniel-Constantin Mierla miconda@gmail.com wrote:
Hello,
what would be the drawback of having sip_msg being all the time in shared memory? Would pkg vs shm operations have relevant impact?
Yes.
From personal observations, most of the requests (over 95%) end in TM module (to absorb retransmission or to forward) where the sip_msg s moved to shm. It would make things simpler for tm callbacks and related routes (no need to move back/forward from/to pkg/shm). Parsing will happen always once, as now cloning to shm in tm discards some parsed headers, which may be needed in failure route or callbacks.
Havin a non-shm copy helps with locking and with moving cache lines between cpus.
as lot of processing is done with the message in shm anyhow, I tried to figure out the impact of the rest of processing. So you say that is better to copy to pkg and re-parse, than working with shm structures.
The access is not sync'ed, as there will be same usage - in one process - just the alloc/free will be different.
Cheers, Daniel