ps utility in linux (procps), how to check which CPU is used

Question

It is about procps package, utility ps for linux.

Can it print the number of last used CPU for each process (thread)?

Update: Not a CPU Time (10 seconds), but a CPU NUMBER (CPU0,CPU5,CPU123)

Answer 1

The ps(1) man page says you can use the psr field:

   psr        PSR     processor that process is currently assigned to.

$ ps -o pid,psr,comm
  PID PSR COMMAND
 7871   1 bash
 9953   3 ps

Or you can use the cpuid field, which does the same thing.

$ ps -o pid,cpuid,comm
  PID CPUID COMMAND
 7871     1 bash
10746     3 ps

The reason for two names is for compatibility with Solaris (psr) and NetBSD/OpenBSD (cpuid).

To get threads too, add the -L option (and the lwp field if you are using -o).

Without threads:

$ ps -U $USER -o pid,psr,comm | egrep 'chromi|PID' | head -4
  PID PSR COMMAND
 6457   3 chromium-browse
 6459   0 chromium-browse
 6461   2 chromium-browse

With threads:

$ ps -U $USER -L -o pid,lwp,psr,comm | egrep 'chromi|PID' | head -4
  PID   LWP PSR COMMAND
 6457  6457   3 chromium-browse
 6457  6464   1 chromium-browse
 6457  6465   2 chromium-browse

There's also an undocumented -P option, which adds psr to the normal fields:

$ ps -U $USER -LP | egrep 'chromi|PID' | head -4
  PID   LWP PSR TTY          TIME CMD
 6457  6457   3 ?        00:01:19 chromium-browse
 6457  6464   1 ?        00:00:00 chromium-browse
 6457  6465   2 ?        00:00:00 chromium-browse

Answer 2

which of multiple processors? it does not offer an option for that according to the manpage. but on my Debian stable system it accepts the undocumented -o cpu

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after looking at the source, and the output of ps L, I believe your answer is either the cpuid or sgi_p output options, column IDs CPUID and P, respectively.

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And 'cpu' should work according to this note in output.c, but it's currently tied to the 'nop' output pr_nop():

{"cpu", "CPU", pr_nop, sr_nop, 3, 0, BSD, AN|RIGHT}, /* FIXME ... HP-UX wants this as the CPU number for SMP? */