From: Jay Vosburgh <jay.vosburgh@canonical.com>
To: paulmck@linux.vnet.ibm.com
Cc: Yanko Kaneti <yaneti@declera.com>,
Josh Boyer <jwboyer@fedoraproject.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Cong Wang <cwang@twopensource.com>, Kevin Fenzi <kevin@scrye.com>,
netdev <netdev@vger.kernel.org>,
"Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>,
mroos@linux.ee, tj@kernel.org
Subject: Re: localed stuck in recent 3.18 git in copy_net_ns?
Date: Fri, 24 Oct 2014 15:41:31 -0700 [thread overview]
Message-ID: <8988.1414190491@famine> (raw)
In-Reply-To: <20141024221602.GB4977@linux.vnet.ibm.com>
Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:
>On Fri, Oct 24, 2014 at 03:02:04PM -0700, Jay Vosburgh wrote:
>> Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:
>>
[...]
>> I've got an ftrace capture from unmodified -net, it looks like
>> this:
>>
>> ovs-vswitchd-902 [000] .... 471.778441: rcu_barrier: rcu_sched Begin cpu -1 remaining 0 # 0
>> ovs-vswitchd-902 [000] .... 471.778452: rcu_barrier: rcu_sched Check cpu -1 remaining 0 # 0
>> ovs-vswitchd-902 [000] .... 471.778452: rcu_barrier: rcu_sched Inc1 cpu -1 remaining 0 # 1
>> ovs-vswitchd-902 [000] .... 471.778453: rcu_barrier: rcu_sched OnlineNoCB cpu 0 remaining 1 # 1
>> ovs-vswitchd-902 [000] .... 471.778453: rcu_barrier: rcu_sched OnlineNoCB cpu 1 remaining 2 # 1
>> ovs-vswitchd-902 [000] .... 471.778453: rcu_barrier: rcu_sched OnlineNoCB cpu 2 remaining 3 # 1
>> ovs-vswitchd-902 [000] .... 471.778454: rcu_barrier: rcu_sched OnlineNoCB cpu 3 remaining 4 # 1
>
>OK, so it looks like your system has four CPUs, and rcu_barrier() placed
>callbacks on them all.
No, the system has only two CPUs. It's an Intel Core 2 Duo
E8400, and /proc/cpuinfo agrees that there are only 2. There is a
potentially relevant-sounding message early in dmesg that says:
[ 0.000000] smpboot: Allowing 4 CPUs, 2 hotplug CPUs
>> ovs-vswitchd-902 [000] .... 471.778454: rcu_barrier: rcu_sched Inc2 cpu -1 remaining 4 # 2
>
>The above removes the extra count used to avoid races between posting new
>callbacks and completion of previously posted callbacks.
>
>> rcuos/0-9 [000] ..s. 471.793150: rcu_barrier: rcu_sched CB cpu -1 remaining 3 # 2
>> rcuos/1-18 [001] ..s. 471.793308: rcu_barrier: rcu_sched CB cpu -1 remaining 2 # 2
>
>Two of the four callbacks fired, but the other two appear to be AWOL.
>And rcu_barrier() won't return until they all fire.
>
>> I let it sit through several "hung task" cycles but that was all
>> there was for rcu:rcu_barrier.
>>
>> I should have ftrace with the patch as soon as the kernel is
>> done building, then I can try the below patch (I'll start it building
>> now).
>
>Sounds very good, looking forward to hearing of the results.
Going to bounce it for ftrace now, but the cpu count mismatch
seemed important enough to mention separately.
-J
---
-Jay Vosburgh, jay.vosburgh@canonical.com
next prev parent reply other threads:[~2014-10-24 22:41 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-20 20:15 localed stuck in recent 3.18 git in copy_net_ns? Kevin Fenzi
2014-10-20 20:43 ` Dave Jones
2014-10-20 20:53 ` Kevin Fenzi
2014-10-21 21:12 ` Kevin Fenzi
2014-10-22 17:12 ` Josh Boyer
2014-10-22 17:37 ` Cong Wang
2014-10-22 17:49 ` Josh Boyer
2014-10-22 17:53 ` Eric W. Biederman
2014-10-22 18:11 ` Paul E. McKenney
2014-10-22 18:25 ` Eric W. Biederman
2014-10-22 18:55 ` Paul E. McKenney
2014-10-22 19:33 ` Josh Boyer
2014-10-22 22:40 ` Yanko Kaneti
2014-10-22 23:24 ` Paul E. McKenney
2014-10-23 6:09 ` Yanko Kaneti
2014-10-23 12:27 ` Paul E. McKenney
2014-10-23 15:33 ` Paul E. McKenney
[not found] ` <CA+5PVA4H6EAf6cBc4a_8W8x4Mgppjc5GsskKaCRry2jq+LP+FA@mail.gmail.com>
2014-10-23 16:28 ` Paul E. McKenney
2014-10-23 19:51 ` Yanko Kaneti
2014-10-23 20:05 ` Paul E. McKenney
2014-10-23 21:45 ` Yanko Kaneti
2014-10-23 22:04 ` Paul E. McKenney
2014-10-24 4:48 ` Jay Vosburgh
2014-10-24 14:50 ` Paul E. McKenney
2014-10-24 18:20 ` Jay Vosburgh
2014-10-24 18:33 ` Paul E. McKenney
2014-10-24 9:08 ` Yanko Kaneti
2014-10-24 15:40 ` Paul E. McKenney
2014-10-24 16:29 ` Yanko Kaneti
2014-10-24 16:54 ` Paul E. McKenney
2014-10-24 17:09 ` Yanko Kaneti
2014-10-24 17:20 ` Paul E. McKenney
2014-10-24 17:35 ` Yanko Kaneti
2014-10-24 18:32 ` Paul E. McKenney
2014-10-24 18:49 ` Jay Vosburgh
2014-10-24 18:57 ` Paul E. McKenney
2014-10-24 20:15 ` Paul E. McKenney
2014-10-24 21:25 ` Yanko Kaneti
2014-10-24 21:49 ` Paul E. McKenney
2014-10-24 22:02 ` Jay Vosburgh
2014-10-24 22:16 ` Paul E. McKenney
2014-10-24 22:41 ` Jay Vosburgh [this message]
2014-10-24 22:34 ` Jay Vosburgh
2014-10-24 22:59 ` Paul E. McKenney
2014-10-24 23:05 ` Paul E. McKenney
2014-10-25 0:20 ` Jay Vosburgh
2014-10-25 2:03 ` Paul E. McKenney
2014-10-25 4:33 ` Jay Vosburgh
2014-10-25 5:16 ` Paul E. McKenney
2014-10-25 16:38 ` Jay Vosburgh
2014-10-25 18:18 ` Paul E. McKenney
2014-10-27 17:45 ` Paul E. McKenney
2014-10-27 20:43 ` Jay Vosburgh
2014-10-27 21:07 ` Paul E. McKenney
2014-10-28 8:12 ` Yanko Kaneti
2014-10-28 12:50 ` Paul E. McKenney
2014-10-28 13:00 ` Yanko Kaneti
2014-10-28 15:54 ` Kevin Fenzi
2014-10-28 16:15 ` Paul E. McKenney
2014-10-25 12:09 ` Yanko Kaneti
2014-10-25 13:38 ` Paul E. McKenney
2014-10-22 17:59 ` Paul E. McKenney
2014-10-22 18:03 ` Josh Boyer
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=8988.1414190491@famine \
--to=jay.vosburgh@canonical.com \
--cc=cwang@twopensource.com \
--cc=ebiederm@xmission.com \
--cc=jwboyer@fedoraproject.org \
--cc=kevin@scrye.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mroos@linux.ee \
--cc=netdev@vger.kernel.org \
--cc=paulmck@linux.vnet.ibm.com \
--cc=tj@kernel.org \
--cc=yaneti@declera.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.