From: Tejun Heo <tj@kernel.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>,
robert.moore@intel.com, lv.zheng@intel.com, rjw@sisk.pl,
lenb@kernel.org, tglx@linutronix.de, mingo@elte.hu,
akpm@linux-foundation.org, trenn@suse.de, yinghai@kernel.org,
jiang.liu@huawei.com, wency@cn.fujitsu.com, laijs@cn.fujitsu.com,
isimatu.yasuaki@jp.fujitsu.com, izumi.taku@jp.fujitsu.com,
mgorman@suse.de, minchan@kernel.org, mina86@mina86.com,
gong.chen@linux.intel.com, vasilis.liaskovitis@profitbricks.com,
lwoodman@redhat.com, riel@redhat.com, jweiner@redhat.com,
prarit@redhat.com, zhangyanfei@cn.fujitsu.com,
yanghy@cn.fujitsu.com, x86@kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-acpi@vger.kernel.org, "Luck,
Tony (tony.luck@intel.com)" <tony.luck@intel.com>
Subject: Re: [PATCH part5 0/7] Arrange hotpluggable memory as ZONE_MOVABLE.
Date: Mon, 12 Aug 2013 11:23:43 -0400 [thread overview]
Message-ID: <20130812152343.GK15892@htj.dyndns.org> (raw)
In-Reply-To: <5208FBBC.2080304@zytor.com>
Hello,
On Mon, Aug 12, 2013 at 08:14:04AM -0700, H. Peter Anvin wrote:
> It gets really messy if it is advisory. Suddenly you have the user
> thinking they can hotswap a memory bank and they just can't.
I'm very skeptical that not doing the strict re-ordering would
increase the chance of reaching memory allocation where hot unplug
would be impossible by much. Given that, it'd be much better to be
able to boot w/o hotunplug capability than to fail boot. The kernel
can whine loudly when hotunplug conditions aren't met but I think that
really is as far as that should go.
> Overall, I'm getting convinced that this whole approach is just doomed
> to failure -- it will not provide the user what they expect and what
> they need, which is to be able to hotswap any particular chunk of
> memory. This means that there has to be a remapping layer, either using
> the TLBs (perhaps leveraging the Xen machine page number) or using
> things like QPI memory routing.
For hot unplug to work in completely generic manner, yeah, there
probably needs to be an extra layer of indirection. Have no idea what
the correct way to achieve that would be tho. I'm also not sure how
practicial memory hot unplug is for physical machines and improving
ballooning could be a better approach for vms.
Thanks.
--
tejun
next prev parent reply other threads:[~2013-08-12 15:23 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-08 10:16 [PATCH part5 0/7] Arrange hotpluggable memory as ZONE_MOVABLE Tang Chen
2013-08-08 10:16 ` [PATCH part5 1/7] x86: get pg_data_t's memory from other node Tang Chen
2013-08-12 14:39 ` Tejun Heo
2013-08-12 15:12 ` Tang Chen
2013-08-08 10:16 ` [PATCH part5 2/7] x86, numa, mem_hotplug: Skip all the regions the kernel resides in Tang Chen
2013-08-08 10:16 ` [PATCH part5 3/7] memblock, numa: Introduce flag into memblock Tang Chen
2013-08-08 10:16 ` [PATCH part5 4/7] memblock, mem_hotplug: Introduce MEMBLOCK_HOTPLUG flag to mark hotpluggable regions Tang Chen
2013-08-08 10:16 ` [PATCH part5 5/7] memblock, mem_hotplug: Make memblock skip hotpluggable regions by default Tang Chen
2013-08-14 21:54 ` Naoya Horiguchi
2013-08-15 5:15 ` Tang Chen
2013-08-08 10:16 ` [PATCH part5 6/7] mem-hotplug: Introduce movablenode boot option to {en|dis}able using SRAT Tang Chen
2013-08-08 10:16 ` [PATCH part5 7/7] x86, numa, acpi, memory-hotplug: Make movablenode have higher priority Tang Chen
2013-08-09 16:32 ` [PATCH part5 0/7] Arrange hotpluggable memory as ZONE_MOVABLE Tejun Heo
2013-08-12 6:33 ` Tang Chen
2013-08-12 8:54 ` Tang Chen
2013-08-12 14:50 ` Tejun Heo
2013-08-12 15:14 ` H. Peter Anvin
2013-08-12 15:23 ` Tejun Heo [this message]
2013-08-12 16:29 ` Tang Chen
2013-08-12 16:46 ` Tejun Heo
2013-08-12 18:23 ` Tang Chen
2013-08-12 20:20 ` Tejun Heo
2013-08-12 20:49 ` Luck, Tony
2013-08-12 20:54 ` Tejun Heo
2013-08-12 20:57 ` H. Peter Anvin
2013-08-12 21:06 ` Yinghai Lu
2013-08-12 21:08 ` Tejun Heo
2013-08-12 21:12 ` H. Peter Anvin
2013-08-12 21:14 ` Tejun Heo
2013-08-12 21:11 ` H. Peter Anvin
2013-08-12 21:11 ` Luck, Tony
2013-08-12 21:25 ` Yinghai Lu
2013-08-12 21:28 ` H. Peter Anvin
2013-08-13 5:14 ` H. Peter Anvin
2013-08-13 6:14 ` Tang Chen
2013-08-13 9:56 ` Tang Chen
2013-08-13 14:38 ` Tejun Heo
2013-08-13 22:33 ` Yinghai Lu
2013-08-14 1:22 ` Tang Chen
2013-08-15 19:06 ` Toshi Kani
2013-08-15 20:28 ` Yinghai Lu
2013-08-16 2:08 ` Tang Chen
2013-08-16 4:21 ` Yinghai Lu
2013-08-19 3:07 ` Tang Chen
2013-08-19 3:28 ` Yinghai Lu
2013-08-15 8:42 ` Tang Chen
2013-08-15 12:19 ` Tejun Heo
2013-08-15 12:44 ` Tang Chen
2013-08-15 12:49 ` Tejun Heo
2013-08-15 12:52 ` Tang Chen
2013-08-15 14:37 ` Yinghai Lu
2013-08-15 14:45 ` Tejun Heo
2013-08-15 15:05 ` Yinghai Lu
2013-08-15 15:10 ` Tejun Heo
2013-08-15 19:49 ` Toshi Kani
2013-08-15 19:08 ` Luck, Tony
2013-08-15 19:34 ` Yinghai Lu
2013-08-15 14:35 ` Yinghai Lu
2013-08-16 1:16 ` Tang Chen
2013-08-12 15:41 ` Tang Chen
2013-08-12 15:46 ` Tejun Heo
2013-08-12 16:19 ` Tang Chen
2013-08-12 16:22 ` Tejun Heo
2013-08-12 17:01 ` Tang Chen
2013-08-12 17:23 ` H. Peter Anvin
2013-08-14 18:22 ` KOSAKI Motohiro
2013-08-12 18:07 ` Tejun Heo
2013-08-14 18:15 ` KOSAKI Motohiro
2013-08-14 18:23 ` Tejun Heo
2013-08-14 19:40 ` KOSAKI Motohiro
2013-08-14 19:55 ` Tejun Heo
2013-08-14 20:29 ` KOSAKI Motohiro
2013-08-14 20:30 ` H. Peter Anvin
2013-08-14 20:35 ` Tejun Heo
2013-08-14 21:17 ` KOSAKI Motohiro
2013-08-14 21:36 ` Tejun Heo
2013-08-15 1:08 ` KOSAKI Motohiro
2013-08-15 1:21 ` Tejun Heo
2013-08-15 1:33 ` Tejun Heo
2013-08-15 1:44 ` KOSAKI Motohiro
2013-08-15 2:22 ` Tejun Heo
2013-08-15 1:38 ` KOSAKI Motohiro
2013-08-15 1:51 ` Tejun Heo
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