[pulseaudio-discuss] shm size

Lennart Poettering lennart at poettering.net
Tue Sep 30 13:00:58 PDT 2008

On Tue, 30.09.08 12:12, Nick Thompson (rextanka at comcast.net) wrote:

> >> Or if these values are unknown, should I just tool around and keep  
> >> reducing
> >> the amount pre-allocated until the audio stack fails?
> >
> > Why would you want to do that?
> Well if you have an embedded system with a limited amount of flash,  
> and main RAM (compared to an x86 desktop) then an allocation of that  
> size does have an impact, so I was looking for ways to slim it down a  
> little.  That's the main reason.  But if this is a good size even for  
> embedded, then so be it.

Does have in impact? In which way?

Again, the size of the file is misleading. It just reflects allocated
address space -- not RAM! Only when we actually use the address space
it will become backed by RAM. And most of the time we don't use
it. Allocating address space is cheap. And allocating a big chunk of
address space is much cheaper than several small ones.

> For x86 this is a flea on a dogs back, for embedded it's a little more  
> noticeable.  But not a show stopper.

Noticeable? How so?


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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