From: Vlastimil Babka <vbabka@suse.cz>
To: Christoph Lameter <cl@linux.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrey Konovalov <andreyknvl@google.com>,
Alexander Potapenko <glider@google.com>
Subject: Re: Store Buffers (was Re: Is it OK to pass non-acquired objects to kfree?)
Date: Thu, 10 Sep 2015 09:38:47 +0200 [thread overview]
Message-ID: <55F13387.4030803@suse.cz> (raw)
In-Reply-To: <alpine.DEB.2.11.1509092047060.3588@east.gentwo.org>
On 09/10/2015 03:47 AM, Christoph Lameter wrote:
> On Wed, 9 Sep 2015, Paul E. McKenney wrote:
>
>> > But then again kfree() contains a barrier() which would block the compiler
>> > from moving anything into the free path.
>>
>> That barrier() is implicit in the fact that kfree() is an external
>> function? Or are my eyes failing me?
Is the "external function" not enough? Does it change e.g. with LTO, or is that
also subject to the aliasing rules (which I admit not knowing exactly)?
>
> kfree at some point calls slab_free(). That function has a barrier. All
> free operations go through it.
SLAB doesn't have such barrier AFAICS. It will put the object on per-cpu cache
and that's it. Only flushing the full cache takes a spin lock.
>
> --
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next prev parent reply other threads:[~2015-09-10 7:38 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-08 7:51 Is it OK to pass non-acquired objects to kfree? Dmitry Vyukov
2015-09-08 14:13 ` Christoph Lameter
2015-09-08 14:41 ` Dmitry Vyukov
2015-09-08 15:13 ` Christoph Lameter
2015-09-08 15:23 ` Dmitry Vyukov
2015-09-08 15:33 ` Christoph Lameter
2015-09-08 15:37 ` Dmitry Vyukov
2015-09-08 17:09 ` Christoph Lameter
2015-09-08 19:24 ` Dmitry Vyukov
2015-09-09 14:02 ` Christoph Lameter
2015-09-09 14:19 ` Dmitry Vyukov
2015-09-09 14:36 ` Christoph Lameter
2015-09-09 15:30 ` Dmitry Vyukov
2015-09-09 15:44 ` Christoph Lameter
2015-09-09 16:09 ` Dmitry Vyukov
2015-09-09 17:56 ` Christoph Lameter
2015-09-09 18:44 ` Paul E. McKenney
2015-09-09 19:01 ` Christoph Lameter
2015-09-09 20:36 ` Paul E. McKenney
2015-09-09 23:23 ` Store Buffers (was Re: Is it OK to pass non-acquired objects to kfree?) Christoph Lameter
2015-09-10 0:08 ` Paul E. McKenney
2015-09-10 0:21 ` Christoph Lameter
2015-09-10 1:10 ` Paul E. McKenney
2015-09-10 1:47 ` Christoph Lameter
2015-09-10 7:38 ` Vlastimil Babka [this message]
2015-09-10 16:37 ` Christoph Lameter
2015-09-10 7:22 ` Vlastimil Babka
2015-09-10 16:36 ` Christoph Lameter
2015-09-09 23:31 ` Is it OK to pass non-acquired objects to kfree? Christoph Lameter
2015-09-10 9:55 ` Dmitry Vyukov
2015-09-10 10:42 ` Jesper Dangaard Brouer
2015-09-10 12:08 ` Dmitry Vyukov
2015-09-10 13:37 ` Eric Dumazet
2015-09-10 12:47 ` Vlastimil Babka
2015-09-10 13:17 ` Dmitry Vyukov
2015-09-10 17:13 ` Paul E. McKenney
2015-09-10 17:21 ` Paul E. McKenney
2015-09-10 17:26 ` Dmitry Vyukov
2015-09-10 17:44 ` Paul E. McKenney
2015-09-10 18:01 ` Christoph Lameter
2015-09-10 18:11 ` Dmitry Vyukov
2015-09-10 18:13 ` Christoph Lameter
2015-09-10 18:26 ` Dmitry Vyukov
2015-09-10 18:56 ` Paul E. McKenney
2015-09-10 22:00 ` Christoph Lameter
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