From: Aneesh Kumar K V <aneesh.kumar@linux.ibm.com>
To: "ying.huang@intel.com" <ying.huang@intel.com>,
Jagdish Gediya <jvgediya@linux.ibm.com>,
Wei Xu <weixugc@google.com>, Yang Shi <shy828301@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Davidlohr Bueso <dave@stgolabs.net>
Cc: Linux MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Greg Thelen <gthelen@google.com>, MichalHocko <mhocko@kernel.org>,
Brice Goglin <brice.goglin@gmail.com>
Subject: Re: [PATCH v2 0/5] mm: demotion: Introduce new node state N_DEMOTION_TARGETS
Date: Mon, 25 Apr 2022 14:24:15 +0530 [thread overview]
Message-ID: <2f716f45-f8c6-a078-6cfc-b4fb5ef74cd5@linux.ibm.com> (raw)
In-Reply-To: <c576a992-5a50-5dd3-644c-a45d4338fc85@linux.ibm.com>
On 4/25/22 1:39 PM, Aneesh Kumar K V wrote:
> On 4/25/22 11:40 AM, ying.huang@intel.com wrote:
>> On Mon, 2022-04-25 at 09:20 +0530, Aneesh Kumar K.V wrote:
>>> "ying.huang@intel.com" <ying.huang@intel.com> writes:
>>>
>>>> Hi, All,
>>>>
>>>> On Fri, 2022-04-22 at 16:30 +0530, Jagdish Gediya wrote:
>>>>
>>>> [snip]
>>>>
>>>>> I think it is necessary to either have per node demotion targets
>>>>> configuration or the user space interface supported by this patch
>>>>> series. As we don't have clear consensus on how the user interface
>>>>> should look like, we can defer the per node demotion target set
>>>>> interface to future until the real need arises.
>>>>>
>>>>> Current patch series sets N_DEMOTION_TARGET from dax device kmem
>>>>> driver, it may be possible that some memory node desired as demotion
>>>>> target is not detected in the system from dax-device kmem probe path.
>>>>>
>>>>> It is also possible that some of the dax-devices are not preferred as
>>>>> demotion target e.g. HBM, for such devices, node shouldn't be set to
>>>>> N_DEMOTION_TARGETS. In future, Support should be added to distinguish
>>>>> such dax-devices and not mark them as N_DEMOTION_TARGETS from the
>>>>> kernel, but for now this user space interface will be useful to avoid
>>>>> such devices as demotion targets.
>>>>>
>>>>> We can add read only interface to view per node demotion targets
>>>>> from /sys/devices/system/node/nodeX/demotion_targets, remove
>>>>> duplicated /sys/kernel/mm/numa/demotion_target interface and instead
>>>>> make /sys/devices/system/node/demotion_targets writable.
>>>>>
>>>>> Huang, Wei, Yang,
>>>>> What do you suggest?
>>>>
>>>> We cannot remove a kernel ABI in practice. So we need to make it right
>>>> at the first time. Let's try to collect some information for the
>>>> kernel
>>>> ABI definitation.
>>>>
>>>> The below is just a starting point, please add your requirements.
>>>>
>>>> 1. Jagdish has some machines with DRAM only NUMA nodes, but they don't
>>>> want to use that as the demotion targets. But I don't think this is a
>>>> issue in practice for now, because demote-in-reclaim is disabled by
>>>> default.
>>>
>>> It is not just that the demotion can be disabled. We should be able to
>>> use demotion on a system where we can find DRAM only NUMA nodes. That
>>> cannot be achieved by /sys/kernel/mm/numa/demotion_enabled. It needs
>>> something similar to to N_DEMOTION_TARGETS
>>>
>>
>> Can you show NUMA information of your machines with DRAM-only nodes and
>> PMEM nodes? We can try to find the proper demotion order for the
>> system. If you can not show it, we can defer N_DEMOTION_TARGETS until
>> the machine is available.
>
>
> Sure will find one such config. As you might have noticed this is very
> easy to have in a virtualization setup because the hypervisor can assign
> memory to a guest VM from a numa node that doesn't have CPU assigned to
> the same guest. This depends on the other guest VM instance config
> running on the system. So on any virtualization config that has got
> persistent memory attached, this can become an easy config to end up with.
>
>
something like this
$ numactl -H
available: 2 nodes (0-1)
node 0 cpus: 0 1 2 3 4 5 6 7
node 0 size: 14272 MB
node 0 free: 13392 MB
node 1 cpus:
node 1 size: 2028 MB
node 1 free: 1971 MB
node distances:
node 0 1
0: 10 40
1: 40 10
$ cat /sys/bus/nd/devices/dax0.0/target_node
2
$
# cd /sys/bus/dax/drivers/
:/sys/bus/dax/drivers# ls
device_dax kmem
:/sys/bus/dax/drivers# cd device_dax/
:/sys/bus/dax/drivers/device_dax# echo dax0.0 > unbind
:/sys/bus/dax/drivers/device_dax# echo dax0.0 > ../kmem/new_id
:/sys/bus/dax/drivers/device_dax# numactl -H
available: 3 nodes (0-2)
node 0 cpus: 0 1 2 3 4 5 6 7
node 0 size: 14272 MB
node 0 free: 13380 MB
node 1 cpus:
node 1 size: 2028 MB
node 1 free: 1961 MB
node 2 cpus:
node 2 size: 0 MB
node 2 free: 0 MB
node distances:
node 0 1 2
0: 10 40 80
1: 40 10 80
2: 80 80 10
:/sys/bus/dax/drivers/device_dax#
next prev parent reply other threads:[~2022-04-25 8:55 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-13 9:22 [PATCH v2 0/5] mm: demotion: Introduce new node state N_DEMOTION_TARGETS Jagdish Gediya
2022-04-13 9:22 ` [PATCH v2 1/5] mm: demotion: Set demotion list differently Jagdish Gediya
2022-04-14 7:09 ` ying.huang
2022-04-14 8:48 ` Jagdish Gediya
2022-04-14 8:57 ` ying.huang
2022-04-14 8:55 ` Baolin Wang
2022-04-14 9:02 ` Jonathan Cameron
2022-04-14 10:40 ` Jagdish Gediya
2022-04-21 6:13 ` ying.huang
2022-04-13 9:22 ` [PATCH v2 2/5] mm: demotion: Add new node state N_DEMOTION_TARGETS Jagdish Gediya
2022-04-21 4:33 ` Wei Xu
2022-04-13 9:22 ` [PATCH v2 3/5] mm: demotion: Add support to set targets from userspace Jagdish Gediya
2022-04-21 4:26 ` Wei Xu
2022-04-22 9:13 ` Jagdish Gediya
2022-04-21 5:31 ` Wei Xu
2022-04-13 9:22 ` [PATCH v2 4/5] device-dax/kmem: Set node state as N_DEMOTION_TARGETS Jagdish Gediya
2022-04-13 9:22 ` [PATCH v2 5/5] mm: demotion: Build demotion list based on N_DEMOTION_TARGETS Jagdish Gediya
2022-04-13 21:44 ` [PATCH v2 0/5] mm: demotion: Introduce new node state N_DEMOTION_TARGETS Andrew Morton
2022-04-14 10:16 ` Jagdish Gediya
2022-04-14 7:00 ` ying.huang
2022-04-14 10:19 ` Jagdish Gediya
2022-04-21 3:11 ` Yang Shi
2022-04-21 5:41 ` Wei Xu
2022-04-21 6:24 ` ying.huang
2022-04-21 6:49 ` Wei Xu
2022-04-21 7:08 ` ying.huang
2022-04-21 7:29 ` Wei Xu
2022-04-21 7:45 ` ying.huang
2022-04-21 18:26 ` Wei Xu
2022-04-22 0:58 ` ying.huang
2022-04-22 4:46 ` Wei Xu
2022-04-22 5:40 ` ying.huang
2022-04-22 6:13 ` Wei Xu
2022-04-22 6:21 ` ying.huang
2022-04-22 11:00 ` Jagdish Gediya
2022-04-22 16:43 ` Wei Xu
2022-04-22 17:29 ` Yang Shi
2022-04-24 3:02 ` ying.huang
2022-04-25 3:50 ` Aneesh Kumar K.V
2022-04-25 6:10 ` ying.huang
2022-04-25 8:09 ` Aneesh Kumar K V
2022-04-25 8:54 ` Aneesh Kumar K V [this message]
2022-04-25 20:17 ` Davidlohr Bueso
2022-04-26 8:42 ` ying.huang
2022-04-26 9:02 ` Aneesh Kumar K V
2022-04-26 9:44 ` ying.huang
2022-04-27 4:27 ` Wei Xu
2022-04-25 7:26 ` Jagdish Gediya
2022-04-25 16:56 ` Wei Xu
2022-04-27 5:06 ` Aneesh Kumar K V
2022-04-27 18:27 ` Wei Xu
2022-04-28 0:56 ` ying.huang
2022-04-28 4:11 ` Wei Xu
2022-04-28 17:14 ` Yang Shi
2022-04-29 1:27 ` Alistair Popple
2022-04-29 2:21 ` ying.huang
2022-04-29 2:58 ` Wei Xu
2022-04-29 3:27 ` ying.huang
2022-04-29 4:45 ` Alistair Popple
2022-04-29 18:53 ` Yang Shi
2022-04-29 18:52 ` Yang Shi
2022-04-27 7:11 ` ying.huang
2022-04-27 16:27 ` Wei Xu
2022-04-28 8:37 ` ying.huang
[not found] ` <DM6PR11MB4107867291AFE0C210D9052ADCFD9@DM6PR11MB4107.namprd11.prod.outlook.com>
2022-04-30 2:21 ` Wei Xu
2022-04-21 17:56 ` Yang Shi
2022-04-21 23:48 ` ying.huang
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