From: Haicheng Li <haicheng.li@linux.intel.com>
To: paulmck@linux.vnet.ibm.com
Cc: Pavel Machek <pavel@ucw.cz>,
akpm@linux-foundation.org, linux-mm@kvack.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Andi Kleen <ak@linux.intel.com>,
Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>,
Len Brown <len.brown@intel.com>,
"Rafael J. Wysocki" <rjw@sisk.pl>,
Yinghai Lu <yinghai@kernel.org>, Thomas Renninger <trenn@suse.de>,
David Rientjes <rientjes@google.com>, Mel Gorman <mel@csn.ul.ie>,
Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>,
Alex Chiang <achiang@hp.com>, Tejun Heo <tj@kernel.org>,
Christoph Lameter <cl@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@suse.de>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Shaohua Li <shaohua.li@intel.com>,
Hugh Dickins <hugh.dickins@tiscali.co.uk>,
James Bottomley <James.Bottomley@HansenPartnership.com>,
linux-kernel@vger.kernel.org,
linux-pm@lists.linux-foundation.org, linux-acpi@vger.kernel.org,
fengguang.wu@intel.com, shaohui.zheng@linux.intel.com
Subject: Re: [RFC,5/7] NUMA hotplug emulator
Date: Mon, 17 May 2010 10:42:17 +0800 [thread overview]
Message-ID: <4BF0AD09.80404@linux.intel.com> (raw)
In-Reply-To: <20100516174502.GI2418@linux.vnet.ibm.com>
Paul E. McKenney wrote:
> On Fri, May 07, 2010 at 04:11:42PM +0200, Pavel Machek wrote:
>> Hi!
>>
>>> hotplug emulator: Abstract cpu register functions
>>>
>>> Abstract function arch_register_cpu and register_cpu, move the implementation
>>> details to a sub function with prefix "__".
>>>
>>> each of the sub function has an extra parameter nid, it can be used to register
>>> CPU under a fake NUMA node, it is a reserved interface for cpu hotplug emulation
>>> (CPU PROBE/RELEASE) in x86.
>> I don't get it. CPU hotplug can already be tested using echo 0/1 >
>> online, and that works on 386. How is this different?
"echo 0/1 > online" is logical cpu online/offline.
The emulator intends to emulate physical add/remove of cpus.
They cover different code path.
You can get details of the terms via $KERN_SRC/Documentation/cpu-hotplug.txt.
>> It seems to add some numa magic. Why is it important?
In real world, numa affinity info of the cpus is required for physical cpu hotadd/remove
, which finally affects related data structures and code path. Emulator need the ability
to emulate it.
> My guess is that he wants to test the software surrounding NUMA on a
> non-NUMA (or different-NUMA) machine, perhaps in order to shake out bugs
> before the corresponding hardware is available.
This is one of the purposes. Auto tests and debugging all can get benefits from such emulation.
-haicheng
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next prev parent reply other threads:[~2010-05-17 2:42 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-13 11:56 [RFC,5/7] NUMA hotplug emulator Shaohui Zheng
2010-05-07 14:11 ` Pavel Machek
2010-05-16 17:45 ` Paul E. McKenney
2010-05-17 2:42 ` Haicheng Li [this message]
2010-05-17 3:37 ` Shaohui Zheng
2010-05-17 9:39 ` Andi Kleen
2010-05-17 9:38 ` Andi Kleen
2010-05-13 12:11 ` Jean Delvare
-- strict thread matches above, loose matches on Subject: below --
2010-05-13 12:14 Shaohui Zheng
2010-05-14 5:49 ` Paul Mundt
2010-05-18 9:03 ` Shaohui Zheng
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