From: Michal Hocko <mhocko@kernel.org> To: Andrew Morton <akpm@linux-foundation.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, Reza Arbab <arbab@linux.vnet.ibm.com>, Yasuaki Ishimatsu <yasu.isimatu@gmail.com>, qiuxishi@huawei.com, Igor Mammedov <imammedo@redhat.com>, Vitaly Kuznetsov <vkuznets@redhat.com>, <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org> Subject: [PATCH 0/2] mm, memory_hotplug: redefine memory offline retry logic Date: Mon, 4 Sep 2017 10:21:46 +0200 [thread overview] Message-ID: <20170904082148.23131-1-mhocko@kernel.org> (raw) Hi, while testing memory hotplug on a large 4TB machine we have noticed that memory offlining is just too eager to fail. The primary reason is that the retry logic is just too easy to give up. We have 4 ways out of the offline - we have a permanent failure (isolation or memory notifiers fail, or hugetlb pages cannot be dropped) - userspace sends a signal - a hardcoded 120s timeout expires - page migration fails 5 times This is way too convoluted and it doesn't scale very well. We have seen both temporary migration failures as well as 120s being triggered. After removing those restrictions we were able to pass stress testing during memory hot remove without any other negative side effects observed. Therefore I suggest dropping both hard coded policies. I couldn't have found any specific reason for them in the changelog. I neither didn't get any response [1] from Kamezawa. If we need some upper bound - e.g. timeout based - then we should have a proper and user defined policy for that. In any case there should be a clear use case when introducing it. Any comments, objections? Shortlog Michal Hocko (2): mm, memory_hotplug: do not fail offlining too early mm, memory_hotplug: remove timeout from __offline_memory Diffstat mm/memory_hotplug.c | 48 ++++++++++++------------------------------------ 1 file changed, 12 insertions(+), 36 deletions(-) [1] http://lkml.kernel.org/r/20170828094316.GF17097@dhcp22.suse.cz
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org> To: Andrew Morton <akpm@linux-foundation.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, Reza Arbab <arbab@linux.vnet.ibm.com>, Yasuaki Ishimatsu <yasu.isimatu@gmail.com>, qiuxishi@huawei.com, Igor Mammedov <imammedo@redhat.com>, Vitaly Kuznetsov <vkuznets@redhat.com>, linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org> Subject: [PATCH 0/2] mm, memory_hotplug: redefine memory offline retry logic Date: Mon, 4 Sep 2017 10:21:46 +0200 [thread overview] Message-ID: <20170904082148.23131-1-mhocko@kernel.org> (raw) Hi, while testing memory hotplug on a large 4TB machine we have noticed that memory offlining is just too eager to fail. The primary reason is that the retry logic is just too easy to give up. We have 4 ways out of the offline - we have a permanent failure (isolation or memory notifiers fail, or hugetlb pages cannot be dropped) - userspace sends a signal - a hardcoded 120s timeout expires - page migration fails 5 times This is way too convoluted and it doesn't scale very well. We have seen both temporary migration failures as well as 120s being triggered. After removing those restrictions we were able to pass stress testing during memory hot remove without any other negative side effects observed. Therefore I suggest dropping both hard coded policies. I couldn't have found any specific reason for them in the changelog. I neither didn't get any response [1] from Kamezawa. If we need some upper bound - e.g. timeout based - then we should have a proper and user defined policy for that. In any case there should be a clear use case when introducing it. Any comments, objections? Shortlog Michal Hocko (2): mm, memory_hotplug: do not fail offlining too early mm, memory_hotplug: remove timeout from __offline_memory Diffstat mm/memory_hotplug.c | 48 ++++++++++++------------------------------------ 1 file changed, 12 insertions(+), 36 deletions(-) [1] http://lkml.kernel.org/r/20170828094316.GF17097@dhcp22.suse.cz -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next reply other threads:[~2017-09-04 8:22 UTC|newest] Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-09-04 8:21 Michal Hocko [this message] 2017-09-04 8:21 ` [PATCH 0/2] mm, memory_hotplug: redefine memory offline retry logic Michal Hocko 2017-09-04 8:21 ` [PATCH 1/2] mm, memory_hotplug: do not fail offlining too early Michal Hocko 2017-09-04 8:21 ` Michal Hocko 2017-09-05 6:29 ` Anshuman Khandual 2017-09-05 6:29 ` Anshuman Khandual 2017-09-05 7:13 ` Michal Hocko 2017-09-05 7:13 ` Michal Hocko 2017-09-08 17:26 ` Vlastimil Babka 2017-09-08 17:26 ` Vlastimil Babka 2017-09-11 8:17 ` Michal Hocko 2017-09-11 8:17 ` Michal Hocko 2017-09-13 11:41 ` Vlastimil Babka 2017-09-13 11:41 ` Vlastimil Babka 2017-09-13 12:10 ` Michal Hocko 2017-09-13 12:10 ` Michal Hocko 2017-09-13 12:14 ` Michal Hocko 2017-09-13 12:14 ` Michal Hocko 2017-09-13 12:19 ` Vlastimil Babka 2017-09-13 12:19 ` Vlastimil Babka 2017-09-13 12:32 ` Michal Hocko 2017-09-13 12:32 ` Michal Hocko 2017-09-04 8:21 ` [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory Michal Hocko 2017-09-04 8:21 ` Michal Hocko 2017-09-04 8:58 ` Xishi Qiu 2017-09-04 8:58 ` Xishi Qiu 2017-09-04 9:01 ` Michal Hocko 2017-09-04 9:01 ` Michal Hocko 2017-09-04 9:05 ` Xishi Qiu 2017-09-04 9:05 ` Xishi Qiu 2017-09-04 9:15 ` Michal Hocko 2017-09-04 9:15 ` Michal Hocko 2017-09-05 5:46 ` Anshuman Khandual 2017-09-05 5:46 ` Anshuman Khandual 2017-09-05 7:23 ` Michal Hocko 2017-09-05 7:23 ` Michal Hocko 2017-09-05 8:54 ` Anshuman Khandual 2017-09-05 8:54 ` Anshuman Khandual 2017-09-08 17:27 ` Vlastimil Babka 2017-09-08 17:27 ` Vlastimil Babka
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20170904082148.23131-1-mhocko@kernel.org \ --to=mhocko@kernel.org \ --cc=akpm@linux-foundation.org \ --cc=arbab@linux.vnet.ibm.com \ --cc=imammedo@redhat.com \ --cc=kamezawa.hiroyu@jp.fujitsu.com \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-mm@kvack.org \ --cc=qiuxishi@huawei.com \ --cc=vkuznets@redhat.com \ --cc=yasu.isimatu@gmail.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.