[LAU] Ardour memory usage -- was Re: A short story: from zero to recording the drums in a budget

[Robin Gareus]

Hi,

Let me pick up this thread again.

On 07/22/2014 11:54 AM, Fons Adriaensen wrote:
> On Mon, Jul 21, 2014 at 11:19:47PM -1000, Joel Roth wrote:
>> Carlo Ascani wrote:
>>> 2014-07-22 10:23 GMT+02:00 Fons Adriaensen <fons at linuxaudio.org>:
>>>>
>>>> I've got a similar setup: 512M, Arch + windowmaker,
>>>> but can't get A3 to run on it in any usable way - it
>>>> just eats too much memory.

It's amazing, even my now almost 7 year old Thinkpad came with 2GB RAM,
and asking around, most people have at least 4, or 8 GB RAM these days.

Still, Ardour3's memory usage just became [much] better.
(git cairocanvas branch)

>>>> Any tricks ??

yes, see below.

>>> And honestly, the only thing I am able to do with so little ram
>>> is to record.  No way I can do editing, and plugins neither.
>>
> It's A3 taking something like 330 MB just for an empty
> session. The only thing I'd want to do with this system
> is recording (which worked perfectly well for years using
> A2), no plugins or anything else.
>

An empty session is down to 96MB RSS now, (20MB on the heap, the rest
for code+stacks), a bit more when running with jackd instead of Ardour's
ALSA backend (100-200MB depending on jack's i/o count - but that mem is
shared with jackd and actually jackd's). Adding a track to ardour adds
about 2MB per channel (default 5 sec buffers @48KSPS for in/out) to that.

Previously an empty session took around 300MB RSS here. Depending on how
you do statistics, that's an improvement of over 300%.

To optimize further: Compiling ardour without lv2 and VST support can
help. The initial plugin scan (at application start) can still use quite
a bit, depending on the number of plugins and the plugins themselves.
That memory is now free()ed before the session is loaded, but there can
be initial peaks.

There are a few more places where memory consumption could be optimized
but the time it'd take to squeeze out the last few MBytes is likely
worth much more than buying all remaining users with only 512MB RAM an
extra GB :)

Kudos to the valgrind team and their brilliant massif tool!

Cheers!
robin