Re: [patch 0/9] mutex subsystem, -V4

On Thu, 22 Dec 2005, Sean wrote:

> On Thu, December 22, 2005 6:34 pm, Christoph Hellwig said:
> > On Thu, Dec 22, 2005 at 03:30:14PM -0800, Andrew Morton wrote:
> >> No it does not.
> >>
> >> Ingo's work has shown us two things:
> >>
> >> a) semaphores use more kernel text than they should and
> >>
> >> b) semaphores are less efficient than they could be.
> >>
> >> Fine.  Let's update the semaphore implementation to fix those things.
> >> Nobody has addressed this code in several years.  If we conclusively
> >> cannot
> >> fix these things then that's the time to start looking at implementing
> >> new
> >> locking mechanisms.
> >
> > c) semaphores are total overkill for 99% percent of the users.  Remember
> > this thing about optimizing for the common case?
> >
> > Pretty much everywhere we do want mutex semantic.  So let's have a proper
> > primitive exactly for that, and we can keep the current semaphore
> > implementation (with a much simpler implementation) for that handfull of
> > users in the kernel that really want a counting semaphore.
> >
> > I really don't get why you hate mutex primitives so much.
> >
>
> Yes it's hard to figure.  It seems to be deeper than just hating mutex
> primitives, he hates the timer core updates that come from Ingo too; this
> may be a general dislike for all things -rt.

Andrew can surely answer that, but it could be something as
simple as wanting to build a more stable kernel (one without
so much churn), so that things have time to mature and
improve without breaking so many other things...

This (current) is a hectic development cycle style.
-- 
~Randy
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