Subject: Re: [linux-audio-dev] Performance problems caused by dlopen()
From: Anders Torger (torger_AT_ludd.luth.se)
Date: Sat Oct 05 2002 - 13:19:04 EEST
On Saturday 05 October 2002 11.01, you wrote:
> On Saturday 05 October 2002 10.51, you wrote:
> > On Sat, Oct 05, 2002 at 09:12:31 +0200, Anders Torger wrote:
> > > Although I have disabled the use of the dlopen()'d modules (for
> > > debugging this problem), running the init code in the beginning
> > > causes the convolution loop to take 109ms instead of 62ms.
> >
> > Just a guess, but it could be cache related. I've had exteme
> > performance changes when things end up just fitting in the cache or
> > just not.
>
> Yes, it probably is in some way (to my knowledge, this only occurs
> when I have quite large blocks to process), however, the task and
> data is the same for both cases, the difference is that some
> unrelated code has been run in a dlopen'd module before it. The
> work-around I'm doing now is to fork the convolution process early,
> before any dlopen stuff, it makes the initialisation much more
> cumbersome, but the performance problem goes away.
Uhh... it seems to be totally unrelated to anything... just some
spurious cache problem, sometimes, if the code is executed in a
particular order, the memory layout is beneficial, sometimes it is not.
dlopen seems to have nothing to do with it. I just have to live with
it...
/Anders Torger
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