Subject: Re: [linux-audio-dev] shared memory synchronization
From: Benno Senoner (sbenno_AT_gardena.net)
Date: pe loka 01 1999 - 12:58:23 EDT
On Fri, 01 Oct 1999, est_AT_hyperreal.org wrote:
> Juhana Sadeharju discourseth:
> > >From: est_AT_hyperreal.org
> > >
> > >Some of the recent discussions, especially the anomalous behavior
> > >observed by Juhana, have got me thinking about three issues involving
> > >the use of shared memory between threads and among processors.
> >
> > I have recently suspected that the corresponding page just was swapped
> > out.
>
> Wouldn't the access cause a page fault (and swap-in) if that were the case?
>
> > I don't exactly recall when I upgraded memory from 16 to 32 Mbytes
> > but when I had 16 Mbytes, the system swapped easily. Perhaps locking
> > of allocated pages would help...? I could test this with XWave2.
>
> A small test program that illustrates the behavior would be ideal.
>
> Eric
I tested the behavior on my box,
(no code handy in this moment .. sorry)
but it works,
I have one task writing values to shmem, and the other
printing the values:
the values show up about 10-20ms later,
(when you printf the kernel has to schedule the X server)
which is the scheduling interval on a HZ=100 box.
Therefore I assume that there is nothing wrong.
Benno.
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