[SR-Dev] what if ...

[Daniel-Constantin Mierla]

On 05/20/2009 07:31 PM, Andrei Pelinescu-Onciul wrote:
> On May 20, 2009 at 19:24, Daniel-Constantin Mierla <miconda at 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

-- 
Daniel-Constantin Mierla
http://www.asipto.com/