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Message-ID: <504ECEA2.4010805@cn.fujitsu.com> Date: Tue, 11 Sep 2012 13:39:46 +0800 From: Wen Congyang <wency@...fujitsu.com> To: Jerry <uulinux@...il.com> CC: Minchan Kim <minchan@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>, Vasilis Liaskovitis <vasilis.liaskovitis@...fitbricks.com>, x86@...nel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, linux-acpi@...r.kernel.org, linux-s390@...r.kernel.org, linux-sh@...r.kernel.org, linux-ia64@...r.kernel.org, cmetcalf@...era.com, sparclinux@...r.kernel.org, rientjes@...gle.com, liuj97@...il.com, len.brown@...el.com, benh@...nel.crashing.org, paulus@...ba.org, cl@...ux.com, kosaki.motohiro@...fujitsu.com Subject: Re: [RFC v8 PATCH 00/20] memory-hotplug: hot-remove physical memory At 09/11/2012 01:18 PM, Jerry Wrote: > Hi Kim, > > Thank you for your kindness. Let me clarify this: > > On ARM architecture, there are 32 bits physical addresses space. However, > the addresses space is divided into 8 banks normally. Each bank > disabled/enabled by a chip selector signal. In my platform, bank0 connects > a DDR chip, and bank1 also connects another DDR chip. And each DDR chip > whose capability is 512MB is integrated into the main board. So, it could > not be removed by hand. We can disable/enable each bank by peripheral > device controller registers. > > When system enter suspend state, if all the pages allocated could be > migrated to one bank, there are no valid data in the another bank. In this > time, I could disable the free bank. It isn't necessary to provided power > to this chip in the suspend state. When system resume, I just need to > enable it again. > > Hi Wen, > > I am sorry for that I doesn't know the "_PSx support" means. Maybe I > needn't it. Hmm, arm doesn't support ACPI, so please ignore it. Thanks Wen Congyang > > Thanks, > Jerry > > 2012/9/11 Minchan Kim <minchan@...nel.org> > >> Hi Jerry, >> >> On Tue, Sep 11, 2012 at 08:27:40AM +0800, Jerry wrote: >>> Hi Wen, >>> >>> I have been arranged a job related memory hotplug on ARM architecture. >>> Maybe I know some new issues about memory hotplug on ARM architecture. I >>> just enabled it on ARM, and it works well in my Android tablet now. >>> However, I have not send out my patches. The real reason is that I don't >>> know how to do it. Maybe I need to read >> "Documentation/SubmittingPatches". >>> >>> Hi Andrew, >>> This is my first time to send you a e-mail. I am so nervous about if I >> have >>> some mistakes or not. >> >> Don't be afraid. >> If you might make a mistake, it's very natural to newbie. >> I am sure anyone doesn't blame you. :) >> If you have a good patch, please send out. >> >>> >>> Some peoples maybe think memory hotplug need to be supported by special >>> hardware. Maybe it means memory physical hotplug. Some times, we just >> need >>> to use memory logical hotplug, doesn't remove the memory in physical. It >> is >>> also usefully for power saving in my platform. Because I doesn't want >>> the offline memory is in *self-refresh* state. >> >> Just out of curiosity. >> What's the your scenario and gain? >> AFAIK, there were some effort about it in embedded side but gain isn't >> rather big >> IIRC. >> >>> >>> Any comments are appreciated. >>> >>> Thanks, >>> Jerry >>> >>> 2012/9/10 Vasilis Liaskovitis <vasilis.liaskovitis@...fitbricks.com> >>> >>>> Hi, >>>> >>>> On Mon, Sep 10, 2012 at 10:01:44AM +0800, Wen Congyang wrote: >>>>> At 09/10/2012 09:46 AM, Yasuaki Ishimatsu Wrote: >>>>>> Hi Wen, >>>>>> >>>>>> 2012/09/01 5:49, Andrew Morton wrote: >>>>>>> On Tue, 28 Aug 2012 18:00:07 +0800 >>>>>>> wency@...fujitsu.com wrote: >>>>>>> >>>>>>>> This patch series aims to support physical memory hot-remove. >>>>>>> >>>>>>> I doubt if many people have hardware which permits physical memory >>>>>>> removal? How would you suggest that people with regular hardware >> can >>>>>>> test these chagnes? >>>>>> >>>>>> How do you test the patch? As Andrew says, for hot-removing memory, >>>>>> we need a particular hardware. I think so too. So many people may >> want >>>>>> to know how to test the patch. >>>>>> If we apply following patch to kvm guest, can we hot-remove memory >> on >>>>>> kvm guest? >>>>>> >>>>>> http://lists.gnu.org/archive/html/qemu-devel/2012-07/msg01389.html >>>>> >>>>> Yes, if we apply this patchset, we can test hot-remove memory on kvm >>>> guest. >>>>> But that patchset doesn't implement _PS3, so there is some >> restriction. >>>> >>>> the following repos contain the patchset above, plus 2 more patches >> that >>>> add >>>> PS3 support to the dimm devices in qemu/seabios: >>>> >>>> https://github.com/vliaskov/seabios/commits/memhp-v2 >>>> https://github.com/vliaskov/qemu-kvm/commits/memhp-v2 >>>> >>>> I have not posted the PS3 patches yet in the qemu list, but will post >> them >>>> soon for v3 of the memory hotplug series. If you have issues testing, >> let >>>> me >>>> know. >>>> >>>> thanks, >>>> >>>> - Vasilis >>>> >>>> -- >>>> To unsubscribe, send a message with 'unsubscribe linux-mm' in >>>> the body to majordomo@...ck.org. For more info on Linux MM, >>>> see: http://www.linux-mm.org/ . >>>> Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a> >>>> >>> >>> >>> >>> -- >>> I love linux!!! >> >> -- >> Kind regards, >> Minchan Kim >> > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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