[sr-dev] new memory allocator proposal: TLSF

[Daniel-Constantin Mierla]

Hi Camille,

sounds very interesting, thanks for spending efforts on it!

>From the commit logs I noticed it is only for shm now, right?

The log about enabling it:

- use
    MEMMNG=1 MEMDBG=0 extra_defs='-DTLSF_MALLOC=1
  to enable


Does it still require q_malloc? In other words, is it built on top of
q_malloc?

The code can be merged right now if the new mem manager is disabled by
default. We can review and test thoroughly during next period and polish
the options to enable it.

Cheers,
Daniel

On 22/04/15 11:18, Camille Oudot wrote:
> Hi,
>
> == Short story:
>
> Currently, there is a (corner case) performance issue in kamailio when
> lots of fragments of about the same size are freed in a short time.
>
> == Long story:
>
> I've recently hit a wall using kamailio, dealing with ~150k TLS
> connections in parallel: when I stop my injector (sipp), all the
> connections are closed at the same time. The TCP main process took ~20
> minutes to dispose of all the objects, and was unable to accept any new
> connection in the meantime.
>
> The bottleneck lies in the shm_free() code (whether f_malloc or q_malloc
> is used), when a free fragment is be inserted in an ordered linked list
> (which is O(n) if n is the size of the list). Enabling mem_join did
> help a little (less fragments, shorter lists), and the 150k
> disconnections scenario went down to ~5 minutes unavailability for the
> TCP main process. But this is still big.
>
> == TLSF:
>
> I looked for alternatives to f/q_malloc, and I found TLSF:
>
>   * http://www.gii.upv.es/tlsf/
>
> This allocator has O(1) malloc and free even in every case. This means
> no surprise like the one I had previously.
>
> I took the implementation found here:
>
>   * http://tlsf.baisoku.org/
>
> and integrated it in kamailio. My 150k disconnections scenario went
> down to 12 seconds, and the fragmentation is as good as q_malloc() with
> mem_join.
>
> I've published a branch with TLSF here:
>
>   * https://github.com/kamailio/kamailio/commits/tmp/TLSF_malloc
>
> What do you think of integrating it in kamailio?
>
> By the way, I've tried to play with dl_malloc, ll_malloc and sf_malloc,
> but none of these currently compile. Should we maintain them or remove
> them from the codebase?
>

-- 
Daniel-Constantin Mierla
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio World Conference, May 27-29, 2015
Berlin, Germany - http://www.kamailioworld.com