[lkml]   [2007]   [May]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: + fix-spellings-of-slab-allocator-section-in-init-kconfig.patch added to -mm tree
On Wed, May 09, 2007 at 12:02:29PM +1000, Nick Piggin wrote:
> BTW, we _really_ should be doing RCU properly in slob, because you
> technically can't noop RCU on UP (even though the current users may be
> safe...).

Thanks. Hugh was pretty convinced it was unneeded:

And since I didn't care much about the SMP case, I didn't pursue it.

This almost looks reasonable. I think HW_ALIGN | RCU is going to make
it break though:

> + if (unlikely(c->flags & SLAB_DESTROY_BY_RCU))
> + b += sizeof(struct slob_rcu);
> +

That could be dealt with by putting the slob_rcu at the end of the
object and having the RCU helper function use ->size to work backward
to the actual pointer.

> void kmem_cache_free(struct kmem_cache *c, void *b)
> {
> if (c->dtor)
> c->dtor(b, c, 0);

I think if we want RCU to actually work, we want to run ->dtor in

> - if (c->size < PAGE_SIZE)
> - slob_free(b, c->size);
> - else
> - free_pages((unsigned long)b, find_order(c->size));
> + if (unlikely(c->flags & SLAB_DESTROY_BY_RCU)) {
> + struct slob_rcu *slob_rcu;
> + b -= sizeof(struct slob_rcu);
> + slob_rcu = b;
> + slob_rcu->size = c->size;

Which means just store c in the header^Wfooter, then we can retrieve the size
and the dtor in the RCU helper.

We might as well add slab_is_available and make the damn thing work on
sparsemem again too.

Mathematics is the supreme nostalgia of our time.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2007-05-09 05:01    [W:0.113 / U:3.580 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site