tuna: fix the check of PF_NO_SETAFFINITY flag for threadsHEADtuna.korg/mastermaster

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>

1 files changed, 11 insertions, 2 deletions

diff --git a/tuna/tuna.py b/tuna/tuna.py
index 3c30f03..1de63b0 100755
--- a/tuna/tuna.py
+++ b/tuna/tuna.py
@@ -181,6 +181,15 @@ def cannot_set_affinity(self, pid):
 		except:
 			return True
 
+# FIXME: move to python-linux-procfs
+def cannot_set_thread_affinity(self, pid, tid):
+		PF_NO_SETAFFINITY = 0x04000000
+		try:
+			return int(self.processes[pid].threads[tid]["stat"]["flags"]) & \
+				PF_NO_SETAFFINITY and True or False
+		except:
+			return True
+
 def move_threads_to_cpu(cpus, pid_list, set_affinity_warning = None,
 			spread = False):
 	changed = False
@@ -357,7 +366,7 @@ def isolate_cpus(cpus, nr_cpus):
 			continue
 		threads = ps[pid]["threads"]
 		for tid in threads.keys():
-			if cannot_set_affinity(ps, tid):
+			if cannot_set_thread_affinity(ps, pid, tid):
 				continue
 			try:
 				affinity = schedutils.get_affinity(tid)
@@ -425,7 +434,7 @@ def include_cpus(cpus, nr_cpus):
 			continue
 		threads = ps[pid]["threads"]
 		for tid in threads.keys():
-			if cannot_set_affinity(ps, tid):
+			if cannot_set_thread_affinity(ps, pid, tid):
 				continue
 			try:
 				affinity = schedutils.get_affinity(tid)