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Re: why does rwlock prefer readers by default?
- From: Torvald Riegel <triegel at redhat dot com>
- To: OndÅej BÃlka <neleai at seznam dot cz>
- Cc: GLIBC Devel <libc-alpha at sourceware dot org>
- Date: Mon, 12 May 2014 16:20:22 +0200
- Subject: Re: why does rwlock prefer readers by default?
- Authentication-results: sourceware.org; auth=none
- References: <1399458831 dot 32485 dot 12625 dot camel at triegel dot csb> <20140510170443 dot GC11500 at domone>
On Sat, 2014-05-10 at 19:04 +0200, OndÅej BÃlka 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.