tree 7d95b189d7042ed700581baa9687ad8a7b1d7b8d
parent 756e762eaccb12d277890cfee6cc9eec4a8eba3e
author Daniel Bristot de Oliveira <bristot@redhat.com> 1448649414 -0200
committer Arnaldo Carvalho de Melo <acme@redhat.com> 1448652057 -0300

tuna: fix the check of PF_NO_SETAFFINITY flag for threads

Tuna checks if PF_NO_SETAFFINITY is set on /proc/PID/stat's 'flag' field
to verify if it is possible to migrate a process/thread.  This is
working fine for process, but not for threads.

For threads, the file /proc/TID/stat is being checked, but this file
does not exist as the stat file of a thread is at
/proc/PID/task/TID/stat.  Hence, the check was failing and threads were
not being migrated.

This patch adds a function to check thread's stat file, and this
function is called to verify the PF_NO_SETAFFINITY flag for threads.

Committer note:

Before, doing:

  # tuna --cpu 3 --isolate
  # tuna -t firefox -CP
                      thread       ctxt_switches
      pid SCHED_ rtpri affinity voluntary nonvoluntary             cmd
   14838   OTHER     0    0,1,2    873954        27498         firefox
    14857  OTHER     0  0,1,2,3         3            1  Gecko_IOThread
    14858  OTHER     0  0,1,2,3         1            0    Link Monitor
    14859  OTHER     0  0,1,2,3    126717        12214   Socket Thread
  <SNIP>

So it affected just the main thread, all the children remained with
their existing affinity mask.

After the patch:

  # tuna --cpu 3 --isolate
  # tuna -t firefox -CP
                        thread       ctxt_switches
      pid SCHED_ rtpri affinity voluntary nonvoluntary             cmd
   14838   OTHER     0    0,1,2    877488        27583         firefox
    14857  OTHER     0    0,1,2         3            1  Gecko_IOThread
    14858  OTHER     0    0,1,2         1            0    Link Monitor
    14859  OTHER     0    0,1,2    126933        12235   Socket Thread
  <SNIP>

Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Kastner <jkastner@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Tuna <tuna-devel@lists.fedorahosted.org>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1286221
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>