From: Tejun Heo <tj@kernel.org>
To: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>,
linux-kernel@vger.kernel.org, laijs@cn.fujitsu.com,
isimatu.yasuaki@jp.fujitsu.com, tangchen@cn.fujitsu.com,
izumi.taku@jp.fujitsu.com
Subject: Re: [PATCH 0/2] workqueue: fix a bug when numa mapping is changed
Date: Tue, 31 Mar 2015 23:02:42 -0400 [thread overview]
Message-ID: <20150401030242.GL9974@htj.duckdns.org> (raw)
In-Reply-To: <551B5E0F.1020302@jp.fujitsu.com>
On Wed, Apr 01, 2015 at 11:55:11AM +0900, Kamezawa Hiroyuki wrote:
> Now, hot-added cpus will have the lowest free cpu id.
>
> Because of this, in most of systems which has only cpu-hot-add, cpu-ids are always
> contiguous even after cpu hot add.
> In enterprise, this would be considered as imcompatibility.
>
> determining cpuid <-> lapicid at boot will make cpuids sparse. That may corrupt
> exisiting script or configuration/resource management software.
Ugh... so, cpu number allocation on hot-add is part of userland
interface that we're locked into? Tying hotplug and id allocation
order together usually isn't a good idea. What if the cpu up fails
while running the notifiers? The ID is already allocated and the next
cpu being brought up will be after a hole anyway. Is this even
actually gonna affect userland?
--
tejun
next prev parent reply other threads:[~2015-04-01 3:02 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-26 2:17 [PATCH 0/2] workqueue: fix a bug when numa mapping is changed Gu Zheng
2015-03-26 2:17 ` [PATCH 1/2] x86/cpu hotplug: make apicid <--> cpuid mapping persistent Gu Zheng
2015-03-26 3:19 ` Kamezawa Hiroyuki
2015-03-26 4:55 ` Gu Zheng
2015-03-26 15:13 ` Tejun Heo
2015-03-26 16:31 ` Kamezawa Hiroyuki
2015-03-30 9:58 ` Gu Zheng
2015-04-01 2:59 ` Kamezawa Hiroyuki
2015-03-26 2:17 ` [PATCH 2/2] workqueue: update per cpu workqueue's numa affinity when cpu preparing online Gu Zheng
2015-03-26 3:12 ` [PATCH 0/2] workqueue: fix a bug when numa mapping is changed Kamezawa Hiroyuki
2015-03-26 5:04 ` Gu Zheng
2015-03-26 15:18 ` Tejun Heo
2015-03-26 16:42 ` Kamezawa Hiroyuki
2015-03-30 9:49 ` Gu Zheng
2015-03-30 9:49 ` Gu Zheng
2015-03-31 6:09 ` Kamezawa Hiroyuki
2015-03-31 15:28 ` Tejun Heo
2015-04-01 2:55 ` Kamezawa Hiroyuki
2015-04-01 3:02 ` Tejun Heo [this message]
2015-04-01 3:05 ` Tejun Heo
2015-04-01 8:30 ` Kamezawa Hiroyuki
2015-04-02 1:36 ` Gu Zheng
2015-04-02 2:54 ` Kamezawa Hiroyuki
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