why does rwlock prefer readers by default?

[Torvald Riegel]

On Sat, 2014-05-10 at 19:04 +0200, Ondřej Bílka wrote:
> On Wed, May 07, 2014 at 12:33:51PM +0200, Torvald Riegel wrote:
> > POSIX makes it an implementation-defined choice whether readers or
> > writers are preferred.  Our current implementation's default is that
> > readers are to be preferred.  I couldn't find the rationale for this;
> > does anybody know what it was?
> > 
> > Otherwise, if this was an arbitrary choice, what do you all think the
> > default should be?  Can we change it?  Should we change it to preferring
> > writers?
> 
> I realized that for this discussion we should sort issues with assembly
> rwlock implementations first. If we decide that some behaviour is
> preffered we should keep it consistent on all architectures or it will
> remain undefined for crossplatform programs.
> 
> It need either maintainers review and modify rwlock code or remove
> assembly implementation. As I doubt that now assembly helps I would
> check architectures if that is case before doing change.

The background for my question is a new rwlock implementation using a
different algorithm, and having no assembly variants. Thus, this would
be independent of what you seem to think about.