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

["Sean" <seanlkml@sympatico.ca>]

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.

Sean