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Date: Thu, 7 Mar 2002 10:42:41 -0500
From: Arjan van de Ven <arjanv@redhat.com>
To: Hubertus Franke <frankeh@watson.ibm.com>
Cc: arjanv@redhat.com, Rusty Russell <rusty@rustcorp.com.au>,
        linux-kernel@vger.kernel.org
Subject: Re: furwocks: Fast Userspace Read/Write Locks
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In-Reply-To: <20020307153228.3A6773FE06@smtp.linux.ibm.com>; from frankeh@watson.ibm.com on Thu, Mar 07, 2002 at 10:33:32AM -0500
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On Thu, Mar 07, 2002 at 10:33:32AM -0500, Hubertus Franke wrote:
> On Thursday 07 March 2002 07:50 am, Arjan van de Ven wrote:
> > Rusty Russell wrote:
> > > This is a userspace implementation of rwlocks on top of futexes.
> >
> > question: if rwlocks aren't actually slower in the fast path than
> > futexes,
> > would it make sense to only do the rw variant and in some userspace
> > layer
> > map "traditional" semaphores to write locks ?
> > Saves half the implementation and testing....
> > -
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> 
> I m not in favor of that. The dominant lock will be mutexes.

if there's no extra cost I don't care which is dominant; having one well
tested path is worth it then. If there is extra cost then yes a split is
better.
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