How to find the cause for high CPU usage of gnome-shell?

Question

I'm on a Linux Fedora 23 and I recently noticed that my gnome-shell process constantly uses 100% of one CPU (reported by htop, no visible applications running). There are some hints out there which cover some workarounds for bugs in the gnome-shell (deactivating background logo, re-aligning the monitors) but none of them help.

I tried to run

perf top

which reports the most work in the following symbols:

22.55%  [kernel]                            [k] acpi_ns_search_one_scope
11.41%  [kernel]                            [k] acpi_ex_system_memory_space_h
 5.27%  [kernel]                            [k] _raw_spin_lock_irqsave
 5.23%  [kernel]                            [k] _raw_write_unlock_irqrestore
 3.52%  [kernel]                            [k] acpi_ut_update_object_referen
 ...

Then I tried to closer look into the gnome-shell process with

perf record -g -p PID
perf report -g

but the output seems to be useless:

  Children      Self  Command      Shared Object                 Symbol       
-   29.08%     0.00%  gnome-shell  [unknown]                     [.] 000000000
   - 0                                                                        
      + 55.88% 0                                                              
      + 8.25% 0x85a81                                                         
      + 6.87% 0x2                                                             
      + 5.94% 0x4                                                             
      + 4.60% 0x889fc                                                         
        3.32% 0x656c6261                                                      
      + 2.39% 0x8feab                                                         
        2.23% 0x88467                                                         
      + 1.26% 0x190800002800                                                  
      + 1.24% 0xffad7fa800100008                                              
        1.23% 0xc82ca96051913c58                                              
        1.20% 0x5602c82afa00                                                  
      + 1.18% 0x1                                                             
        1.16% 0x89e84                                                         
        1.10% 0x5602c7c68830                                                  
        1.08% 0x5602c900736e                                                  
      + 1.08% 0x7ffe4bfd1001                                                  
-   21.48%     0.00%  gnome-shell  [kernel.kallsyms]             [k] entry_SYS
   - entry_SYSCALL_64_fastpath                                                
      + 43.62% __GI___ioctl                                                   
      + 18.92% 0xf6fdd                                                        
      + 12.90% __GI___libc_open                                               
      + 5.21% 0xfb4d                                                          
      + 3.92% __GI___libc_recvmsg                                             
      + 2.89% _IO_file_read                                                   
      + 2.75% __socket                                                        
      + 2.74% __GI___libc_read                                                
      + 1.41% __GI___mmap64                                                   
      + 1.39% __GI___libc_recvmsg                                             
        1.30% 0x103b73                                                        
      + 0.77% __GI___writev                                                   
        0.74% __statfs                                                        
      + 0.74% _IO_file_open                                                   
        0.71% __GI___munmap                                                   
+    9.37%     0.00%  gnome-shell  libc-2.22.so                  [.] __GI___io
+    9.37%     0.00%  gnome-shell  [kernel.kallsyms]             [k] sys_ioctl

Do you have a hint for me what I could do to to inspect what's going on on my system?

I'm on a Skylake i5 6260u with Intel Iris 540 with Fedora running kernel 4.3.3-300.fc23.x86_64

score 15 · Answer 1 · edited Jun 12 '21 at 11:36

Perhaps try using auditd, which would roughly be something like:

sudo yum install auditd  # sudo apt install auditd on Debian
sudo auditctl -a exit,always -S all -F pid=1234 & sleep 15
sudo auditctl -d exit,always -S all -F pid=1234
less /var/log/audit/audit.log

This will install and start auditd, set a policy to capture system call info for your PID (1234 in the example), wait for a short while to capture a decent amount of info, then remove the audit policy. Take a good look over the auditd.log for your gnome-terminal PID, you may get a better idea of what it's busy doing.

Another quick tool for spotting what a process is spending it's time doing is just strace, wait a short time, then hit Ctrl + C:

$ sudo strace -c -p 1234
strace: Process 1234 attached
^Cstrace: Process 1234 detached
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 56.98    0.003496         388         9           clone
 17.19    0.001055           8       135           rt_sigprocmask
  6.19    0.000380          21        18         9 wait4
  4.58    0.000281          16        18           close
  3.80    0.000233          26         9           read
  3.47    0.000213          24         9           stat
  3.37    0.000207          23         9         9 rt_sigsuspend
  3.08    0.000189          21         9           pipe
  1.34    0.000082           9         9         9 rt_sigreturn
------ ----------- ----------- --------- --------- ----------------
100.00    0.006136                   225        27 total

Then if you want to learn more, check the appropriate man page for the system call you're looking at:

$ man -s2 clone

score 4 · Answer 2 · edited Jan 04 '23 at 09:19

There could be several causes of it:

Clock with seconds:

gsettings set org.gnome.desktop.interface clock-show-seconds false

indicator-multiload (CPU etc. usage monitor in bar)

Process could be named in menu: System Load Indicator.

Just stop process (or before stopping it) disable autostart option. Setting longer time for probing also helps, but for example 10 sec. makes the whole app useless.
Anything with "real time" monitoring, disk, CPU, network.

score 1 · Answer 3 · answered Sep 05 '18 at 02:24

1

For anyone who encounters a similar problem. Check that you are using. Xorg or wayland. If the wayland is changed to xorg and everything becomes ok.

answered Sep 05 '18 at 02:24

Someone

57

score 1 · Answer 4 · answered Jun 18 '22 at 04:17

1

I was using indicator-multiload which was using too much CPU even if I set the refresh time to 10 seconds.

I removed it with apt and then I installed gnome-system-monitor which does the same thing but more efficiently.

answered Jun 18 '22 at 04:17

alexg

161

How to find the cause for high CPU usage of gnome-shell?

4 Answers4