After moving from High-Sierra to Mojave I noticed my Mac (23", fusion-drive 3.4GHz) has become much slower. In particular, I noticed that just after the startup I have a significant amount of disk activity.
I investigated this disk activity quite a bit and have come to understand that it's mainly related to the process
kernel_task. I read in many posts about
kernel_task taking the CPU to prevent it from becoming too hot, but I don't think this is my case:
- I have disk activity, not CPU activity
- This disk activity is related to my user (from 500MB to 2GB disk activity at each startup) while other users on the same Mac don't have (about 30MB at each startup).
I tried with multiple tools to understand what may be the source behind this kernel_task writing:
- Activity Monitor: I clearly see the kernel_task as the main contributor to disk activity
log show: Not able to see any indication on a specific process
sudo fs_usage -f filesys: Sometimes I see kernel_task in the list, but without specific indication, just indicating
ps axv: to show startup processes
sudo syscallbypid.d: to list the system calls, with their process
sudo lsof: to list open files
iotacannot be applied because of System Integrity Protection
So basically despite all my efforts shown above, I'm not able to say why in my user, at the startup,
kernel_task writes and reads at least (but even more) few GB.
Are there any other hints to help me understanding what is
kernel_task reading or writing after the startup?