netdev - Re: [PATCH 7/7] slub: initial bulk free implementation

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Message-ID: <20150616112033.0b8bafb8@redhat.com>
Date:	Tue, 16 Jun 2015 11:20:33 +0200
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
Cc:	linux-mm@...ck.org, Christoph Lameter <cl@...ux.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	netdev@...r.kernel.org,
	Alexander Duyck <alexander.duyck@...il.com>, brouer@...hat.com
Subject: Re: [PATCH 7/7] slub: initial bulk free implementation

On Tue, 16 Jun 2015 16:23:28 +0900
Joonsoo Kim <iamjoonsoo.kim@....com> wrote:

> On Mon, Jun 15, 2015 at 05:52:56PM +0200, Jesper Dangaard Brouer wrote:
> > This implements SLUB specific kmem_cache_free_bulk().  SLUB allocator
> > now both have bulk alloc and free implemented.
> > 
> > Play nice and reenable local IRQs while calling slowpath.
> > 
> > Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
> > ---
> >  mm/slub.c |   32 +++++++++++++++++++++++++++++++-
> >  1 file changed, 31 insertions(+), 1 deletion(-)
> > 
> > diff --git a/mm/slub.c b/mm/slub.c
> > index 98d0e6f73ec1..cc4f870677bb 100644
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -2752,7 +2752,37 @@ EXPORT_SYMBOL(kmem_cache_free);
> >  
> >  void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
> >  {
> > -	__kmem_cache_free_bulk(s, size, p);
> > +	struct kmem_cache_cpu *c;
> > +	struct page *page;
> > +	int i;
> > +
> > +	local_irq_disable();
> > +	c = this_cpu_ptr(s->cpu_slab);
> > +
> > +	for (i = 0; i < size; i++) {
> > +		void *object = p[i];
> > +
> > +		if (unlikely(!object))
> > +			continue; // HOW ABOUT BUG_ON()???
> > +
> > +		page = virt_to_head_page(object);
> > +		BUG_ON(s != page->slab_cache); /* Check if valid slab page */
> 
> You need to use cache_from_objt() to support kmemcg accounting.
> And, slab_free_hook() should be called before free.

Okay, but Christoph choose to not support kmem_cache_debug() in patch2/7.

Should we/I try to add kmem cache debugging support?

If adding these, then I would also need to add those on alloc path...

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Sr. Network Kernel Developer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer
--
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