linux-kernel - Re: [PATCH 0/7] slub: Fastpath optimization (especially for RT) V1

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Message-ID: <alpine.DEB.2.11.1412171339450.29803@gentwo.org>
Date:	Wed, 17 Dec 2014 13:44:21 -0600 (CST)
From:	Christoph Lameter <cl@...ux.com>
To:	Joonsoo Kim <js1304@...il.com>
cc:	Joonsoo Kim <iamjoonsoo.kim@....com>, akpm@...uxfoundation.org,
	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linux Memory Management List <linux-mm@...ck.org>,
	Pekka Enberg <penberg@...nel.org>,
	Jesper Dangaard Brouer <brouer@...hat.com>
Subject: Re: [PATCH 0/7] slub: Fastpath optimization (especially for RT) V1

On Wed, 17 Dec 2014, Christoph Lameter wrote:

> On Wed, 17 Dec 2014, Joonsoo Kim wrote:
>
> > +       do {
> > +               tid = this_cpu_read(s->cpu_slab->tid);
> > +               c = this_cpu_ptr(s->cpu_slab);
> > +       } while (IS_ENABLED(CONFIG_PREEMPT) && unlikely(tid != c->tid));

Here is another one without debugging:

   0xffffffff811d23bb <+59>:	mov    %gs:0x8(%r9),%rdx		tid(rdx) = this_cpu_read()
   0xffffffff811d23c0 <+64>:	mov    %r9,%r8
   0xffffffff811d23c3 <+67>:	add    %gs:0x7ee37d9d(%rip),%r8         c (r8) =
   0xffffffff811d23cb <+75>:	cmp    0x8(%r8),%rdx			c->tid == tid
   0xffffffff811d23cf <+79>:	jne    0xffffffff811d23bb <kmem_cache_alloc+59>

Actually that looks ok.

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