From: Vladimir Davydov <vdavydov@parallels.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
linux-mm@kvack.org, Greg Thelen <gthelen@google.com>,
Dave Hansen <dave@sr71.net>,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [patch 1/3] mm: memcontrol: lockless page counters
Date: Mon, 6 Oct 2014 10:38:29 +0400 [thread overview]
Message-ID: <20141006063829.GB1162@esperanza> (raw)
In-Reply-To: <20141003154134.GG4816@dhcp22.suse.cz>
On Fri, Oct 03, 2014 at 05:41:34PM +0200, Michal Hocko wrote:
> On Fri 03-10-14 19:36:23, Vladimir Davydov wrote:
> > On Thu, Oct 02, 2014 at 08:07:48AM -0400, Johannes Weiner wrote:
> [...]
> > > The barriers are implied in change-return atomics, which is why there
> > > is an xchg. But it's clear that this needs to be documented. This?:
> >
> > With the comments it looks correct to me, but I wonder if we can always
> > rely on implicit memory barriers issued by atomic ops. Are there any
> > archs where it doesn't hold?
>
> xchg is explcitly mentioned in Documentation/memory-barriers.txt so it
> is expected to be barrier on all archs. Besides that not all atomic ops
> imply memory barriers. Only those that "modifies some state in memory
> and returns information about the state" do.
Thank you for the info, now it's clear to me.
Thanks,
Vladimir
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next prev parent reply other threads:[~2014-10-06 6:38 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-24 15:43 [patch 0/3] mm: memcontrol: lockless page counters v2 Johannes Weiner
2014-09-24 15:43 ` [patch 1/3] mm: memcontrol: lockless page counters Johannes Weiner
2014-09-26 10:31 ` Vladimir Davydov
2014-10-02 12:07 ` Johannes Weiner
2014-10-03 15:36 ` Vladimir Davydov
2014-10-03 15:41 ` Michal Hocko
2014-10-06 6:38 ` Vladimir Davydov [this message]
2014-09-30 11:06 ` Michal Hocko
2014-10-02 15:01 ` Johannes Weiner
2014-10-02 19:52 ` Johannes Weiner
2014-10-03 15:44 ` Michal Hocko
2014-10-03 14:50 ` Michal Hocko
2014-10-07 15:15 ` Michal Hocko
2014-10-08 12:31 ` Johannes Weiner
2014-09-24 15:43 ` [patch 2/3] mm: hugetlb_controller: convert to " Johannes Weiner
2014-09-26 11:25 ` Vladimir Davydov
2014-10-07 15:21 ` Michal Hocko
2014-10-08 12:39 ` Johannes Weiner
2014-09-24 15:43 ` [patch 3/3] kernel: res_counter: remove the unused API Johannes Weiner
2014-09-26 11:27 ` Vladimir Davydov
2014-10-07 15:26 ` Michal Hocko
-- strict thread matches above, loose matches on Subject: below --
2014-10-14 1:46 [patch 0/3] mm: memcontrol: lockless page counters v3 Johannes Weiner
2014-10-14 1:46 ` [patch 1/3] mm: memcontrol: lockless page counters Johannes Weiner
2014-10-14 15:56 ` Michal Hocko
2014-10-14 16:33 ` Johannes Weiner
2014-10-15 9:40 ` Michal Hocko
2014-10-17 7:47 ` Vladimir Davydov
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