Add k8s mem stat #253
Open
Add k8s mem stat #253
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
To collect k8s memory cgroup statistics, we should check the cgroup version, and then read corresponding memcg path. Signed-off-by: Fei Li <[email protected]>
Signed-off-by: Fei Li <[email protected]>
ShirleyFei
force-pushed
the
add-k8s-mem-stat
branch
from
6cdc030
to
7361863
Compare
The kubelet will terminate end-user pods when the worker node has 'MemoryPressure' according to [1]. But confusingly, there exits two reasons for pods being evicted: - one is the whole machine's free memory is too low, - the other is k8s itself calculation[2], e.i. memory.available[3] is too low. To resolve such confusion for k8s users, collect and show k8s global workingset memory to distinguish between these two causes. Note: 1. Only collect k8s global memory stats is enough, this is because cgroupfs stats are propagated from child to parent. Thus the parent can always notice the change and then updates. And From v1.6 k8s[4], allocatable(/sys/fs/cgroup/memory/kubepods/) is more convincing than capacity(/sys/fs/cgroup/memory/). 2. There are two cgroup drivers or managers to control resources: cgroupfs and systemd[5]. We should take both into account. (The 'systemd' cgroup driver always ends with '.slice') 3. The difference between cgroupv1 and cgroupv2: different field names for memory.stat file, and memory.currentUsage storing in different files (cgv1's memory.usage_in_bytes v.s. cgv2's memory.current). [1]https://kubernetes.io/docs/concepts/scheduling-eviction/node-pressure-eviction/#node-out-of-memory-behavior [2]kubernetes/kubernetes#43916 [3]memory.available = memory.allocatable/capacity - memory.workingSet, memory.workingSet = memory.currentUsage - memory.inactivefile [4]kubernetes/kubernetes#42204 kubernetes/community#348 [5]https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/configure-cgroup-driver/ Signed-off-by: Fei Li <[email protected]> Reported-by: Teng Hu <[email protected]>
ShirleyFei
force-pushed
the
add-k8s-mem-stat
branch
from
7361863
to
15d3102
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
No description provided.