Is there a command in Linux to know the processor number in which a process is loaded?

You can use the ps command to query and display the active processor. For example, you might run:

$ ps -aF
UID        PID  PPID  C    SZ   RSS PSR STIME TTY          TIME CMD
root         1     0  0  5971  1764   1 Sep15 ?        00:00:01 /sbin/init
ubuntu   28903  2975  0  3826  1208   0 09:36 pts/0    00:00:00 ps -aF

The PSR column shows that init is running on processor 1 and ps is running on processor 0. See the manpage for ps(1) for more details on how to customize the fields that are displayed.

You can configure a graphical tool like htop to display the current active processor. Also, htop has a per-CPU load display graph, which may be what you're looking for. See, for example, the following screenshot from http://htop.sourceforge.net/.

Finally, you can use the taskset tool to force affinity to a particular CPU.

There are many ways to find out. htop, top, ps.

htop

• tested version: 1.0.2

• url: http://htop.sourceforge.net/

  1. Hit F2 to get into the setup window
  2. select Columns in the Setup column
  3. go Available Columns
  4. add PROCESSOR
  5. Check the CPU column

top

• tested version: procps 3.3.8

• url: http://gitorious.org/procps

  1. Hit f to get into the Fields Management window
  2. Select P (Last Used Cpu)

here is an example with the last column P

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND   P 
 5626 yashi     20   0 1926276 545964  47596 R  12.6  3.4 151:10.81 gnome-sh+ 2 
 5347 root      20   0  384788  73600  55708 S   8.7  0.5  55:10.09 Xorg      1 
 8125 yashi     20   0  646240  30776  21928 S   4.3  0.2  23:06.20 gnome-sy+ 0 
 1785 yashi     20   0  581180  29288  15560 R   4.0  0.2   0:25.55 gnome-te+ 1

ps

• tested version: procps 3.3.8
• url: http://gitorious.org/procps

PSR is the CODE to display processor id. You can use format option like ps -o pid,psr or simply do ps -eF

$ ps -eF|head
UID        PID  PPID  C    SZ   RSS PSR STIME TTY          TIME CMD
root         1     0  0  3817   964   0 Aug14 ?        00:00:02 init [2]  
root         2     0  0     0     0   2 Aug14 ?        00:00:00 [kthreadd]
root         3     2  0     0     0   0 Aug14 ?        00:00:11 [ksoftirqd/0]
root         5     2  0     0     0   0 Aug14 ?        00:00:00 [kworker/0:0H]
root         7     2  0     0     0   0 Aug14 ?        00:00:00 [migration/0]
root         8     2  0     0     0   0 Aug14 ?        00:00:00 [rcu_bh]
root         9     2  0     0     0   3 Aug14 ?        00:00:39 [rcu_sched]
root        10     2  0     0     0   0 Aug14 ?        00:00:00 [watchdog/0]
root        11     2  0     0     0   1 Aug14 ?        00:00:00 [watchdog/1]