Re: [patch 2/3] NUMA slab locking fixes - move irq disabling from cahep->spinlock to l3 lock

Ravikiran G Thirumalai
2006-02-07T07:50:44Z

On Tue, Feb 07, 2006 at 09:36:40AM +0200, Pekka J Enberg wrote:
> On Mon, 6 Feb 2006, Andrew Morton wrote:
> > > This is getting scary. Manfred, Christoph, Pekka: have you guys taken a
> > > close look at what's going on in here?
>
> On Mon, 6 Feb 2006, Christoph Lameter wrote:
> > I looked at his patch and he seems to be right. Most of the kmem_cache
> > structure is established at slab creation. Updates are to the debug
> > counters and to nodelists[] during node online/offline and to array[]
> > during cpu online/offline. The chain mutex is used to protect the
> > setting of the tuning parameters. I still need to have a look at the
> > details though.
>
> The patch looks correct but I am wondering if we should keep the spinlock
> around for clarity? The chain mutex doesn't really have anything to do
> with the tunables, it's there to protect the cache chain. I am worried
> that this patch makes code restructuring harder. Hmm?

IMHO, if you keep something around which is not needed, it might later get
abused/misused. And what would you add in as comments for the
cachep->spinlock?

Instead, bold comments on cachep structure stating what all members are
protected by which lock/mutex should be sufficient no?

Thanks,
Kiran