mongostats shows 100 % write lock during some specific period. However, during the same period mongotop shows zero write operations on a mongo cluster. 

Could you please clarify how mongostat shows 100 % write lock (lrw column) when there is no write operations seen in mongotop output !

System Configuration

Os Version: CentOS 7
cat /etc/redhat-release
CentOS Linux release 7.6.1810 (Core)
Mongo Version : 3.4.16
Storage Engine: mmapV1
Storage Type: Data Path in tmpfs

[sessionmgr05] out: run: df -hP -x iso9660
[sessionmgr05] out: Filesystem Size Used Avail Use% Mounted on
[sessionmgr05] out: /dev/sda2 95G 19G 71G 22% /
[sessionmgr05] out: devtmpfs 50G 0 50G 0% /dev
[sessionmgr05] out: tmpfs 50G 28K 50G 1% /dev/shm
[sessionmgr05] out: tmpfs 50G 2.1G 48G 5% /run
[sessionmgr05] out: tmpfs 50G 0 50G 0% /sys/fs/cgroup
[sessionmgr05] out: tmpfs 59G 0 59G 0% /var/data/sessions.1
[sessionmgr05] out: tmpfs 9.9G 0 9.9G 0% /run/user/0

Attached mongotop, mongostat outputs  for 100 % write lock periods.