From: "Jan Kratochvil (Azul)" <jkratochvil@azul.com>
To: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, containers@lists.osdl.org,
Waiman Long <longman@redhat.com>
Subject: [PATCH v2] Port hierarchical_{memory,swap}_limit cgroup1->cgroup2
Date: Mon, 12 Feb 2024 12:10:38 +0800 [thread overview]
Message-ID: <ZcmaPqZ9HzoN0GFM@host1.jankratochvil.net> (raw)
Hello,
cgroup1 (by function memcg1_stat_format) already contains two lines
hierarchical_memory_limit %llu
hierarchical_memsw_limit %llu
which are useful for userland to easily and performance-wise find out the
effective cgroup limits being applied. Otherwise userland has to
open+read+close the file "memory.max" and/or "memory.swap.max" in multiple
parent directories of a nested cgroup.
For cgroup1 it was implemented by:
memcg: show real limit under hierarchy mode
https://github.com/torvalds/linux/commit/fee7b548e6f2bd4bfd03a1a45d3afd593de7d5e9
Date: Wed Jan 7 18:08:26 2009 -0800
But for cgroup2 it has been missing so far, this is just a copy-paste of the
cgroup1 code while changing s/memsw/swap/ as that is what cgroup1 vs. cgroup2
tracks. I have added it to the end of "memory.stat" to prevent possible
compatibility problems with existing code parsing that file.
Jan Kratochvil
Signed-off-by: Jan Kratochvil (Azul) <jkratochvil@azul.com>
mm/memcontrol.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 46d8d0211..2631dd810 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1636,6 +1636,8 @@ static inline unsigned long memcg_page_state_local_output(
static void memcg_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
{
int i;
+ unsigned long memory, swap;
+ struct mem_cgroup *mi;
/*
* Provide statistics on the state of the memory subsystem as
@@ -1682,6 +1684,17 @@ static void memcg_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
memcg_events(memcg, memcg_vm_event_stat[i]));
}
+ /* Hierarchical information */
+ memory = swap = PAGE_COUNTER_MAX;
+ for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) {
+ memory = min(memory, READ_ONCE(mi->memory.max));
+ swap = min(swap, READ_ONCE(mi->swap.max));
+ }
+ seq_buf_printf(s, "hierarchical_memory_limit %llu\n",
+ (u64)memory * PAGE_SIZE);
+ seq_buf_printf(s, "hierarchical_swap_limit %llu\n",
+ (u64)swap * PAGE_SIZE);
+
/* The above should easily fit into one page */
WARN_ON_ONCE(seq_buf_has_overflowed(s));
}
next reply other threads:[~2024-02-12 4:10 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-12 4:10 Jan Kratochvil (Azul) [this message]
2024-02-12 15:00 ` [PATCH v2] Port hierarchical_{memory,swap}_limit cgroup1->cgroup2 Michal Koutný
2024-02-12 15:26 ` Waiman Long
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