Re: [PATCH v3] cgroup/dmem: introduce a peak file

[Maarten Lankhorst]

Den 2026-05-22 kl. 18:48, skrev Michal Koutný:
> On Thu, May 14, 2026 at 02:36:08PM -0300, Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxx> wrote:
>> Just like we have memory.peak, introduce a dmem.peak, which uses the
>> page_counter support for that.
>>
>> For now, make it read-only.
>>
>> This allows for memory usage monitoring without polling dmem.current when
>> the information needed is the maximum device memory used. That can be used
>> for capacity planning, such that dmem.max can be properly setup for a given
>> workload. It can also be used for debugging to determine whether a given
>> workload would have caused eviction or system memory use.
>>
>> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxx>
>> ---
>> Changes in v3:
>> - EDITME: describe what is new in this series revision.
>> - EDITME: use bulletpoints and terse descriptions.
>> - Link to v2: https://patch.msgid.link/20260513-dmem_peak-v2-1-dac06999db9e@xxxxxxxxxx
>>
>> Changes in v2:
>> - Make it read-only for now and adjust documentation accordingly.
>> - Link to v1: https://patch.msgid.link/20260506-dmem_peak-v1-0-8d803eb3449c@xxxxxxxxxx
>> ---
>>  Documentation/admin-guide/cgroup-v2.rst |  6 ++++++
>>  kernel/cgroup/dmem.c                    | 15 +++++++++++++++
>>  2 files changed, 21 insertions(+)
>>
>> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
>> index 6efd0095ed99..d103623b2be4 100644
>> --- a/Documentation/admin-guide/cgroup-v2.rst
>> +++ b/Documentation/admin-guide/cgroup-v2.rst
>> @@ -2808,6 +2808,12 @@ DMEM Interface Files
>>  	The semantics are the same as for the memory cgroup controller, and are
>>  	calculated in the same way.
>>  
>> +  dmem.peak
>> +	A read-only nested-keyed file that exists on non-root cgroups.
> 
> s/nested-keyed/flat-keyed/
> 
> 
> With that
> 
> Reviewed-by: Michal Koutný <mkoutny@xxxxxxxx>
Reviewed-by: Maarten Lankhorst <dev@xxxxxxxxxxxx>

With your r-b it's ok to push it to the dmemcg tree?

Kind regards,
~Maarten Lankhorst