helloï¼?linux boss
I found a problem in the process of using linux memcgï¼?When I turned swap off, the memcg memory I created with the following script could not be deleted with echo 0 > memory.force_empty, as explained belowã??
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step1ï¼?swapoff -a
step2ï¼?use this script to create memcg
#!/bin/bash
mkdir -p /tmp/test
for i in 'seq 2000'
do
sudo mkdir -p /sys/fs/cgroup/memory/user.slice/user-0.slice/test$ {i}
sudo echo $$ > /sys/fs/cgroup/memory/user.slice/user-0.slice/test$ {i}/tasks
sudo echo 'data' > /tmp/test/test$ {i}
sudo echo $$ > /sys/fs/cgroup/memory/user.slice/user-0.slice/tasks
sudo rmdir /sys/fs/cgroup/memory/user.slice/user-0.slice/test$ {i}
done
step3ï¼?view /proc/cgroup and /proc/meminfo files
[root@localhost ~]# cat /proc/cgroups
#subsys_name hierarchy num_cgroups enabled
cpuset 10 1 1
cpu 4 1 1
cpuacct 4 1 1
blkio 13 1 1
memory 14 2009 1
devices 6 94 1
[root@localhost ~]# cat /proc/meminfo | grep Percpu
Percpu: 600576 kB
step4ï¼?when I use "echo 0 > /sys/fs/cgroup/memory/user.slice/user-0.slice/memory.force_empty", I find the num_cgroups of memory and percpu have no changed
[root@localhost ~]# echo 0 > /sys/fs/cgroup/memory/user.slice/user-0.slice/memory.force_empty
[root@localhost ~]# cat /proc/cgroups
#subsys_name hierarchy num_cgroups enabled
cpuset 10 1 1
cpu 4 1 1
cpuacct 4 1 1
blkio 13 1 1
memory 14 2039 1
devices 6 87 1
[root@localhost ~]# cat /proc/meminfo | grep Percpu
Percpu: 600576 kB
step 5: when I use swapon -a to open swap, then echo 0 > /sys/fs/cgroup/memory/user.slice/user-0.slice/memory.force_empty again
[root@localhost ~]# swapon -a
[root@localhost ~]# echo 0 > /sys/fs/cgroup/memory/user.slice/user-0.slice/memory.force_empty
step 6: view /proc/cgroup and /proc/meminfo files ,I found the the num_cgroups of memory and percpu have been reduced.
[root@localhost ~]# cat /proc/cgroups
#subsys_name hierarchy num_cgroups enabled
cpuset 10 1 1
cpu 4 1 1
cpuacct 4 1 1
blkio 13 1 1
memory 14 185 1
devices 6 87 1
freezer 9 1 1
[root@localhost ~]# cat /proc/meminfo | grep Percpu
Percpu: 120832 kB
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Therefore, I want to know why swap affects memcg memory reclamation, echo 0 > memory.force_empty this interface should force the memory used by the cgroup to be reclaimed.
I want to know why ,I look forward to hearing back from the community.
Thanks.
