Re: SLUB defrag pull request?
From: Miklos Szeredi
Date: Wed Oct 22 2008 - 03:11:12 EST
On Tue, 21 Oct 2008, Christoph Lameter wrote:
> The only way that a secure reference can be established is if the
> slab page is locked. That requires a spinlock. The slab allocator
> calls the get() functions while the slab lock guarantees object
> existence. Then locks are dropped and reclaim actions can start with
> the guarantee that the slab object will not suddenly vanish.
Yes, you've made up your mind, that you want to do it this way. But
it's the _wrong_ way, this "want to get a secure reference for use
later" leads to madness when applied to dentries or inodes. Try for a
minute to think outside this template.
For example dcache_lock will protect against dentries moving to/from
d_lru. So you can do this:
check if d_lru is non-empty
Yeah, locking will be more complicated in reality. Still, much less
complicated than trying to do the same across two separate phases.
Why can't something like that work?
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/