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 <[email protected]> --- 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/[email protected] Changes in v2: - Make it read-only for now and adjust documentation accordingly. - Link to v1: https://patch.msgid.link/[email protected] --- 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. + + The max device memory usage recorded for the cgroup and its + descendants since the creation of the cgroup for each region. + dmem.capacity A read-only file that describes maximum region capacity. It only exists on the root cgroup. Not all memory can be diff --git a/kernel/cgroup/dmem.c b/kernel/cgroup/dmem.c index 4753a67d0f0f..6430c7ce1e03 100644 --- a/kernel/cgroup/dmem.c +++ b/kernel/cgroup/dmem.c @@ -182,6 +182,11 @@ static u64 get_resource_current(struct dmem_cgroup_pool_state *pool) return pool ? page_counter_read(&pool->cnt) : 0; } +static u64 get_resource_peak(struct dmem_cgroup_pool_state *pool) +{ + return pool ? READ_ONCE(pool->cnt.watermark) : 0; +} + static void reset_all_resource_limits(struct dmem_cgroup_pool_state *rpool) { set_resource_min(rpool, 0); @@ -808,6 +813,11 @@ static int dmemcg_limit_show(struct seq_file *sf, void *v, return 0; } +static int dmem_cgroup_region_peak_show(struct seq_file *sf, void *v) +{ + return dmemcg_limit_show(sf, v, get_resource_peak); +} + static int dmem_cgroup_region_current_show(struct seq_file *sf, void *v) { return dmemcg_limit_show(sf, v, get_resource_current); @@ -856,6 +866,11 @@ static struct cftype files[] = { .name = "current", .seq_show = dmem_cgroup_region_current_show, }, + { + .name = "peak", + .seq_show = dmem_cgroup_region_peak_show, + .flags = CFTYPE_NOT_ON_ROOT, + }, { .name = "min", .write = dmem_cgroup_region_min_write, --- base-commit: d3b0a7f21119f5a66cb76aa28fb8cc13206aaf7d change-id: 20260409-dmem_peak-3abc1be95072 Best regards, -- Thadeu Lima de Souza Cascardo <[email protected]>
