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

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Date:	Tue, 16 Jun 2015 10:04:56 +0200
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	Christoph Lameter <cl@...ux.com>
Cc:	linux-mm@...ck.org, 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 Mon, 15 Jun 2015 11:34:44 -0500 (CDT)
Christoph Lameter <cl@...ux.com> wrote:

> On Mon, 15 Jun 2015, Jesper Dangaard Brouer wrote:
> 
> > +	for (i = 0; i < size; i++) {
> > +		void *object = p[i];
> > +
> > +		if (unlikely(!object))
> > +			continue; // HOW ABOUT BUG_ON()???
> 
> Sure BUG_ON would be fitting here.

Okay, will do in V2.

> > +
> > +		page = virt_to_head_page(object);
> > +		BUG_ON(s != page->slab_cache); /* Check if valid slab page */
> 
> This is the check if the slab page belongs to the slab cache we are
> interested in.

Is this appropriate to keep on this fastpath? (I copied the check from
one of your earlier patches)

> > +
> > +		if (c->page == page) {
> > +			/* Fastpath: local CPU free */
> > +			set_freepointer(s, object, c->freelist);
> > +			c->freelist = object;
> > +		} else {
> > +			c->tid = next_tid(c->tid);
> 
> tids are only useful for the fastpath. No need to fiddle around with them
> for the slowpath.

Okay, understood.

> > +			local_irq_enable();
> > +			/* Slowpath: overhead locked cmpxchg_double_slab */


-- 
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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