Re: [Linuxsampler-devel] optimizations

[Mark K. <mar...@gm...>]

On Sun, 12 Dec 2004 20:01:23 -0500, Vladimir Senkov <ha...@gm...> wrote:
> Hi Everybody,
> 
> It may seem like LS has been quiet for a little while . . .
> But a lot of stuff has been happening behind the scenes.
> Christian and I have been working on optimizations with the goal of
> making LS nothing short of state of the art when it comes to
> efficiency.
> 
> We focused on improving efficiency of real time calculations.
> The project consisted of two major developments:
> 1) Reducing the amount of work and conditionals per sample point
> depending on the state of the voice.
> 2) Developing MMX/SSE(1) implementation for most calculation intensive
> routines (as well as providing a framework for further implementations
> such as SSE2/3, altivec, etc.
> 
> To acomplish task number 1 without introducing branches into the "fast
> path" we've introduced a concept which we called "synthesis mode". An
> entire segment is processed in the same mode.
> Function to process the entire mode is generated using highly
> templated CPP code.
> Ideally (depending on your compiler and options) an entire segment
> will be processed without a single call with only one branch (loop).
> So there is a function for each "synthesis mode" and there is a
> function pointer that is set for a voice before the segment is
> processed.
> 
> To acomplish task number 2 we had to write a few X86 assembly routines
> and do a lot of benchmarking, testing, etc. For some modes we
> acomplished speeds several times faster than CPP implementation.
> Further optimization will be made in some areas.
> We hit a number of issues related to FPU/MMX state problems of Pentium
> and also lots of funny GCC related things. We really wanted to support
> pre-SSE2 processors though.
> 
> Christian is working hard right now on checking everything into the CVS.
> I'd like to point out that there is still some work to be done (as usual) like:
> 1) Some cleanup, putting #if ARCH_X86 in place, etc
> 2) Integrating benchmarking into LS. For now we have separate
> benchmarking suite that we've used but it's not very user friendly and
> up to date, so we are not releasing it at this time. Benchmarking will
> allow users to do wonderful things such as comparing hardware to pick
> best fit for LS, etc.
> 3) cubic interpolation for MMXSSE needs to be implemented at some point
> 4) lots of other things
> 
> There will be subsequent submits to the CVS in the near future so
> please stay tuned!
> 
> --
> Regards,
> Vladimir
> 

Hi,
   I thought that maybe I should try compiling and running LS/QS again
as it's been awhile. I don't like CVS much so I went to Rui's site and
downloaded the newest versions of libgig, liblscp, linuxsampler and
qsampler that he has there.

   I finally managed to get them built. That was a bit of a struggle.
Maybe someone could add the make -f Makefile.cvs step to the INSTALL
file?

   When I tried to run them the qsampler gui comes up fine but when I
tried to load GigaPIano it took a couple of minutes, appeared to use
up a lot of memory, and then crashed and had to be killed.

   This is FC2/PlanetCCRMA with the newest PlanetEdge kernel. The gigs
were on my 1394 audio drive I use with Ardour all the time.

   I know this isn't the most recent version. This note just documents
what I ran into.

- Mark