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Thu, 20 Dec 2018 12:58:17 +0000 (UTC) Subject: Re: [PATCH RFCv2 0/4] mm/memory_hotplug: Introduce memory block types To: linux-mm@kvack.org References: <20181130175922.10425-1-david@redhat.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: <1b4afb6a-5f91-407d-6e6e-6a89b8cf5d56@redhat.com> Date: Thu, 20 Dec 2018 13:58:16 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 MIME-Version: 1.0 In-Reply-To: <20181130175922.10425-1-david@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Thu, 20 Dec 2018 12:58:37 +0000 (UTC) X-Mailman-Approved-At: Fri, 21 Dec 2018 01:05:19 +1100 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Oscar Salvador , "Rafael J. Wysocki" , Michal Hocko , linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , Dave Hansen , Heiko Carstens , Michal Hocko , Vitaly Kuznetsov , Pavel Tatashin , Rich Felker , Arun KS , "H. Peter Anvin" , Stephen Rothwell , Rashmica Gupta , "K. Y. Srinivasan" , Boris Ostrovsky , Paul Mackerras , Pavel Tatashin , linux-s390@vger.kernel.org, Michael Neuling , Stefano Stabellini , Dave Jiang , Yoshinori Sato , Logan Gunthorpe , x86@kernel.org, YueHaibing , Pavel Tatashin , Matthew Wilcox , Ingo Molnar , linux-acpi@vger.kernel.org, Ingo Molnar , xen-devel@lists.xenproject.org, =?UTF-8?Q?Michal_Such=c3=a1nek?= , Len Brown , Fenghua Yu , =?UTF-8?Q?Jan_H=2e_Sch=c3=b6nherr?= , Juergen Gross , Vasily Gorbik , Rob Herring , "mike.travis@hpe.com" , Haiyang Zhang , =?UTF-8?Q?Jonathan_Neusch=c3=a4fer?= , Nicholas Piggin , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Mike Rapoport , Borislav Petkov , Andy Lutomirski , Nathan Fontenot , Stephen Hemminger , Dan Williams , Wei Yang , Joonsoo Kim , Oscar Salvador , Tony Luck , Andrew Banman , Mathieu Malaterre , Greg Kroah-Hartman , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, Mauricio Faria de Oliveira , Thomas Gleixner , Martin Schwidefsky , devel@linuxdriverproject.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, "Kirill A. Shutemov" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 30.11.18 18:59, David Hildenbrand wrote: > This is the second approach, introducing more meaningful memory block > types and not changing online behavior in the kernel. It is based on > latest linux-next. > > As we found out during dicussion, user space should always handle onlining > of memory, in any case. However in order to make smart decisions in user > space about if and how to online memory, we have to export more information > about memory blocks. This way, we can formulate rules in user space. > > One such information is the type of memory block we are talking about. > This helps to answer some questions like: > - Does this memory block belong to a DIMM? > - Can this DIMM theoretically ever be unplugged again? > - Was this memory added by a balloon driver that will rely on balloon > inflation to remove chunks of that memory again? Which zone is advised? > - Is this special standby memory on s390x that is usually not automatically > onlined? > > And in short it helps to answer to some extend (excluding zone imbalances) > - Should I online this memory block? > - To which zone should I online this memory block? > ... of course special use cases will result in different anwers. But that's > why user space has control of onlining memory. > > More details can be found in Patch 1 and Patch 3. > Tested on x86 with hotplugged DIMMs. Cross-compiled for PPC and s390x. > > > Example: > $ udevadm info -q all -a /sys/devices/system/memory/memory0 > KERNEL=="memory0" > SUBSYSTEM=="memory" > DRIVER=="" > ATTR{online}=="1" > ATTR{phys_device}=="0" > ATTR{phys_index}=="00000000" > ATTR{removable}=="0" > ATTR{state}=="online" > ATTR{type}=="boot" > ATTR{valid_zones}=="none" > $ udevadm info -q all -a /sys/devices/system/memory/memory90 > KERNEL=="memory90" > SUBSYSTEM=="memory" > DRIVER=="" > ATTR{online}=="1" > ATTR{phys_device}=="0" > ATTR{phys_index}=="0000005a" > ATTR{removable}=="1" > ATTR{state}=="online" > ATTR{type}=="dimm" > ATTR{valid_zones}=="Normal" > > > RFC -> RFCv2: > - Now also taking care of PPC (somehow missed it :/ ) > - Split the series up to some degree (some ideas on how to split up patch 3 > would be very welcome) > - Introduce more memory block types. Turns out abstracting too much was > rather confusing and not helpful. Properly document them. > > Notes: > - I wanted to convert the enum of types into a named enum but this > provoked all kinds of different errors. For now, I am doing it just like > the other types (e.g. online_type) we are using in that context. > - The "removable" property should never have been named like that. It > should have been "offlinable". Can we still rename that? E.g. boot memory > is sometimes marked as removable ... > Any feedback regarding the suggested block types would be very much appreciated! -- Thanks, David / dhildenb