I am using CentOS 7 with "3.10.0-123.4.2.el7.x86_64" version, but I don't know why the kernel threads named flush aren't present in this kernel version.
I tried to look in the kernel change log, but I didn't find anything.
[root@localhost ~]# ps aux | grep flush [root@localhost ~]# echo $? 1 Without these kernel threads, how are the dirty data flushed?
There are no more dedicated flush threads anymore.
The Linux kernel has moved on to a worker thread model, where several generic worker threads can handle a variety of different tasks. You will see these in the process list as [kworker/#.##]
Unfortunately this new design makes it a bit difficult to tell exactly what any given kworker thread is doing at any given time. But you can rest assured that dirty pages are still being written to disk by one or more of the kworker threads.
