Messages in this thread | | | Date | Thu, 7 Feb 2002 13:15:50 -0700 | From | yodaiken@fsmlabs ... | Subject | Re: [RFC] New locking primitive for 2.5 |
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On Thu, Feb 07, 2002 at 03:08:02PM -0500, Robert Love wrote: > On Thu, 2002-02-07 at 14:58, yodaiken@fsmlabs.com wrote: > > > On Thu, Feb 07, 2002 at 01:40:59PM -0500, Robert Love wrote: > > > We shouldn't engage in wholesale changing of spinlocks to semaphores > > > without a priority-inheritance mechanism. And _that_ is the bigger > > > issue ... > > > > Cool. We can then have the Solaris "this usually doesn't fail on test" priority > > inherit read/write lock. I can hardly wait. > > Or, we could do things right and not.
I'd love to hear how things could be done right here. There seem to be 3 choices for reader writer locks 1. Do the right thing and say no to inheritance: and this means no inheritance on mutexes either. 2. Use the Solaris - "sometimes kinda works" method. 3. Make readers/writer locks very slow and expensive e.g a complete list of reader identities that with atomic insert/delete and with check for uniqueness on insert! Not to mention the write promotion, any interactions between the "favor writes" design it should have and inheritance, links for a mutex inheriting lock to follow down the complete tree of paths from the r/w lock ...
-- --------------------------------------------------------- Victor Yodaiken Finite State Machine Labs: The RTLinux Company. www.fsmlabs.com www.rtlinux.com
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