From: Pavel Tatashin <pasha.tatashin@soleen.com>
To: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <dhildenb@redhat.com>,
Vlastimil Babka <vbabka@suse.cz>, Roman Gushchin <guro@fb.com>,
Bharata B Rao <bharata@linux.ibm.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Shakeel Butt <shakeelb@google.com>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>,
Yafang Shao <laoar.shao@gmail.com>,
stable <stable@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Sasha Levin <sashal@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH v2 00/28] The new cgroup slab memory controller
Date: Wed, 2 Sep 2020 10:20:24 -0400 [thread overview]
Message-ID: <CA+CK2bDAjykqdMrrOEp=NJ28Z4CALXWkHixNMc5tmRYVk75Eig@mail.gmail.com> (raw)
In-Reply-To: <20200902135018.GF4617@dhcp22.suse.cz>
> > This is how we are using it at Microsoft: there is a very large
> > number of small memory machines (8G each) with low downtime
> > requirements (reboot must be under a second). There is also a large
> > state ~2G of memory that we need to transfer during reboot, otherwise
> > it is very expensive to recreate the state. We have 2G of system
> > memory memory reserved as a pmem in the device tree, and use it to
> > pass information across reboots. Once the information is not needed we
> > hot-add that memory and use it during runtime, before shutdown we
> > hot-remove the 2G, save the program state on it, and do the reboot.
>
> I still do not get it. So what does guarantee that the memory is
> offlineable in the first place?
It is in a movable zone, and we have more than 2G of free memory for
successful migrations.
> Also what is the difference between
> offlining and simply shutting the system down so that the memory is not
> used in the first place. In other words what kind of difference
> hotremove makes?
For performance reasons during system updates/reboots we do not erase
memory content. The memory content is erased only on power cycle,
which we do not do in production.
Once we hot-remove the memory, we convert it back into DAXFS PMEM
device, format it into EXT4, mount it as DAX file system, and allow
programs to serialize their states to it so they can read it back
after the reboot.
During startup we mount pmem, programs read the state back, and after
that we hotplug the PMEM DAX as a movable zone. This way during normal
runtime we have 8G available to programs.
Pasha
next prev parent reply other threads:[~2020-09-02 14:28 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-27 17:34 [PATCH v2 00/28] The new cgroup slab memory controller Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 01/28] mm: kmem: cleanup (__)memcg_kmem_charge_memcg() arguments Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 02/28] mm: kmem: cleanup memcg_kmem_uncharge_memcg() arguments Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 03/28] mm: kmem: rename memcg_kmem_(un)charge() into memcg_kmem_(un)charge_page() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 04/28] mm: kmem: switch to nr_pages in (__)memcg_kmem_charge_memcg() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 05/28] mm: memcg/slab: cache page number in memcg_(un)charge_slab() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 06/28] mm: kmem: rename (__)memcg_kmem_(un)charge_memcg() to __memcg_kmem_(un)charge() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 07/28] mm: memcg/slab: introduce mem_cgroup_from_obj() Roman Gushchin
2020-02-03 16:05 ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 08/28] mm: fork: fix kernel_stack memcg stats for various stack implementations Roman Gushchin
2020-02-03 16:12 ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 09/28] mm: memcg/slab: rename __mod_lruvec_slab_state() into __mod_lruvec_obj_state() Roman Gushchin
2020-02-03 16:13 ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 10/28] mm: memcg: introduce mod_lruvec_memcg_state() Roman Gushchin
2020-02-03 17:39 ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 11/28] mm: slub: implement SLUB version of obj_to_index() Roman Gushchin
2020-02-03 17:44 ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 12/28] mm: vmstat: use s32 for vm_node_stat_diff in struct per_cpu_nodestat Roman Gushchin
2020-02-03 17:58 ` Johannes Weiner
2020-02-03 18:25 ` Roman Gushchin
2020-02-03 20:34 ` Johannes Weiner
2020-02-03 22:28 ` Roman Gushchin
2020-02-03 22:39 ` Johannes Weiner
2020-02-04 1:44 ` Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 13/28] mm: vmstat: convert slab vmstat counter to bytes Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 14/28] mm: memcontrol: decouple reference counting from page accounting Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 15/28] mm: memcg/slab: obj_cgroup API Roman Gushchin
2020-02-03 19:31 ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 16/28] mm: memcg/slab: allocate obj_cgroups for non-root slab pages Roman Gushchin
2020-02-03 18:27 ` Johannes Weiner
2020-02-03 18:34 ` Roman Gushchin
2020-02-03 20:46 ` Johannes Weiner
2020-02-03 21:19 ` Roman Gushchin
2020-02-03 22:29 ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 17/28] mm: memcg/slab: save obj_cgroup for non-root slab objects Roman Gushchin
2020-02-03 19:53 ` Johannes Weiner
2020-01-27 17:34 ` [PATCH v2 18/28] mm: memcg/slab: charge individual slab objects instead of pages Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 19/28] mm: memcg/slab: deprecate memory.kmem.slabinfo Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 20/28] mm: memcg/slab: move memcg_kmem_bypass() to memcontrol.h Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 21/28] mm: memcg/slab: use a single set of kmem_caches for all memory cgroups Roman Gushchin
2020-02-03 19:50 ` Johannes Weiner
2020-02-03 20:58 ` Roman Gushchin
2020-02-03 22:17 ` Johannes Weiner
2020-02-03 22:38 ` Roman Gushchin
2020-02-04 1:15 ` Roman Gushchin
2020-02-04 2:47 ` Johannes Weiner
2020-02-04 4:35 ` Roman Gushchin
2020-02-04 18:41 ` Johannes Weiner
2020-02-05 15:58 ` Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 22/28] mm: memcg/slab: simplify memcg cache creation Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 23/28] mm: memcg/slab: deprecate memcg_kmem_get_cache() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 24/28] mm: memcg/slab: deprecate slab_root_caches Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 25/28] mm: memcg/slab: remove redundant check in memcg_accumulate_slabinfo() Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 26/28] tools/cgroup: add slabinfo.py tool Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 27/28] tools/cgroup: make slabinfo.py compatible with new slab controller Roman Gushchin
2020-01-30 2:17 ` Bharata B Rao
2020-01-30 2:44 ` Roman Gushchin
2020-01-31 22:24 ` Roman Gushchin
2020-02-12 5:21 ` Bharata B Rao
2020-02-12 20:42 ` Roman Gushchin
2020-01-27 17:34 ` [PATCH v2 28/28] kselftests: cgroup: add kernel memory accounting tests Roman Gushchin
2020-01-30 2:06 ` [PATCH v2 00/28] The new cgroup slab memory controller Bharata B Rao
2020-01-30 2:41 ` Roman Gushchin
2020-08-12 23:16 ` Pavel Tatashin
2020-08-12 23:16 ` Pavel Tatashin
2020-08-12 23:18 ` Pavel Tatashin
2020-08-12 23:18 ` Pavel Tatashin
2020-08-13 0:04 ` Roman Gushchin
2020-08-13 0:31 ` Pavel Tatashin
2020-08-13 0:31 ` Pavel Tatashin
2020-08-28 16:47 ` Pavel Tatashin
2020-08-28 16:47 ` Pavel Tatashin
2020-09-01 5:28 ` Bharata B Rao
2020-09-01 12:52 ` Pavel Tatashin
2020-09-01 12:52 ` Pavel Tatashin
2020-09-02 6:23 ` Bharata B Rao
2020-09-02 12:34 ` Pavel Tatashin
2020-09-02 12:34 ` Pavel Tatashin
2020-09-02 9:53 ` Vlastimil Babka
2020-09-02 10:39 ` David Hildenbrand
2020-09-02 12:42 ` Pavel Tatashin
2020-09-02 12:42 ` Pavel Tatashin
2020-09-02 13:50 ` Michal Hocko
2020-09-02 14:20 ` Pavel Tatashin [this message]
2020-09-02 14:20 ` Pavel Tatashin
2020-09-03 18:09 ` David Hildenbrand
2020-09-02 11:26 ` Michal Hocko
2020-09-02 12:51 ` Pavel Tatashin
2020-09-02 12:51 ` Pavel Tatashin
2020-09-02 13:51 ` Michal Hocko
2020-09-02 11:32 ` Michal Hocko
2020-09-02 12:53 ` Pavel Tatashin
2020-09-02 12:53 ` Pavel Tatashin
2020-09-02 13:52 ` Michal Hocko
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