tech-kern archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: uvm locking inconsistency

On Thu, Jun 16, 2011 at 02:40:06PM +1000, matthew green wrote:
> > On Wed, Jun 15, 2011 at 09:30:17PM +0200, Manuel Bouyer wrote:
> > > I fear so, sadly. I think DIAGNOSTIC should be back in x86 GENERIC
> > > kernels on HEAD (this can be switched off in release branches)
> > 
> > Contrary, I think every viable debug option (DIAGNOSTIC + LOCKDEBUG at
> > least) should be enabled in HEAD, but disabled in release kernels. An easy
> > way to catch obvious regression that should never enter a release kernel.
> > The so-called HEAD is the main development branch, after all...
> LOCKDEBUG is too expensive for a normal kernel.  eg, isn't
> just a little slower, it's 3-10x slower.

Also, LOCKDEBUG add extra locks which serialize things, so it can actually
hide bugs. Although LOCKDEBUG is a very usefull tool, I don't think it
should be on by default on HEAD. DIAGNOSTIC should.

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference

Home | Main Index | Thread Index | Old Index