Re: Help: multithreaded GNOME app

[Jeff Garzik <jgarzik pobox com>]

On Mon, 1 Feb 1999, Jason Tackaberry wrote:
> > ??  man pipe.  It allocates two descriptors for you, one read, and one
> > write.  If you want bi-directional communication, create two pipes.
> 
> Quite right.  Forgive my stupidity -- I thought pipe linked together two
> already-allocated file descriptors.
> 
> > For speed, you only want to send read or write a single byte to the
> > pipe.  This is sufficient to wake up the process.  Do not use the pipe
> > to pass data larger than sizeof(void*) to the main process, doing so is
> > very wasteful. 
> 
> One byte is all I'd use, yeah.  Is there some low-level rationale behind why
> passing data specifically larger than sizeof(void *) is wasteful?  Something
> to do with the memory bus?

Since you are using threads, anything passed via a pipe from one thread
to another is useless data copying, since the threads share the same
dataspace.  Anything less than sizeof(void*) can be excused, IMHO,
because it is often easier to pass a simple pointer or integer directly
rather than signal, via the pipe, that said pointer/int needs to read.

	Jeff