all mutexes -> read-write locks?

[Ed Schouten]

Hello Julian,

* Julian Elischer <julian at elischer.org> wrote:
> it has been mentioned several times that through the evolution of the
> locking primitives it has come to be that mutexes and exclusively  
> acquired reader-writer locks are almost the same in terms of  overhead
> and that it might be a good move to define all mutexes to be
> actually just that.
>
> this would allow people to slowly go through the system, catching low
> hanging fruit by converting some of the mutex operations to reader
> acquisitions wherever a writer is not required, thus reducing general  
> system contention.
>
> Is there any thought on this?  Last I heard jhb had confirmed that it
> was feasible..

If this is going to be done, could we have mtx_* macro's pointing to the
proper read/write ops? I know, it's just names, but I think most novice
FreeBSD kernel hackers will almost instantaneously figure out what 'mtx'
stands for.

Why not make read/write locking a fundamental part of 'mtx' itself, if
it doesn't introduce much overhead?

-- 
 Ed Schouten <ed at 80386.nl>
 WWW: http://80386.nl/
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