cmdline: Fix IRQ affinity setting

Description of problem:
tuna skips some IRQ threads when applying CPU IRQ affinity with --move
option.

Version-Release number of selected component (if applicable):
tuna-0.9.4-1.el5rt

How reproducible:
always

Steps to Reproduce:
   # users            affinity
.... snip ....
  64 eth0-0             0xffff  bnx2
  65 eth0-1             0xffff  bnx2
  66 eth0-2             0xffff  bnx2
  67 eth0-3             0xffff  bnx2
  68 eth0-4             0xffff  bnx2
  69 eth0-5             0xffff  bnx2
  70 eth0-6             0xffff  bnx2
  71 eth0-7             0xffff  bnx2

Actual results:
.... snip ....
  64 eth0-0             0xffff  bnx2
  65 eth0-1               0xff  bnx2
  66 eth0-2             0xffff  bnx2
  67 eth0-3               0xff  bnx2
  68 eth0-4             0xffff  bnx2
  69 eth0-5               0xff  bnx2
  70 eth0-6             0xffff  bnx2
  71 eth0-7               0xff  bnx2

Expected results:
.... snip ....
  64 eth0-0               0xff  bnx2
  65 eth0-1               0xff  bnx2
  66 eth0-2               0xff  bnx2
  67 eth0-3               0xff  bnx2
  68 eth0-4               0xff  bnx2
  69 eth0-5               0xff  bnx2
  70 eth0-6               0xff  bnx2
  71 eth0-7               0xff  bnx2

Additional info:
tuna GUI can set IRQ affinity correctly.

Comment 1 Rogan Kyuseok Lee 2010-12-23 21:41:19 EST

                elif o in ("-q", "--irqs"):
                        (op, a) = pick_op(a)
                        op_list = reduce(lambda i, j: i + j,
                                         map(irq_mapper, list(set(a.split(",")))))
                        irq_list = do_list_op(op, irq_list, op_list)
                        # See comment above about thread_list_str
                        if not op_list and type(a) == type(''):
                                irq_list_str = do_list_op(op, irq_list_str,
                                                          a.split(","))
                        if not op:
                                thread_list = []
                        if not ps:
                                ps = procfs.pidstats()
                        if tuna.has_threaded_irqs(ps):
                                for irq in irq_list:
                                        irq_re = tuna.threaded_irq_re(irq)
                                        irq_threads = ps.find_by_regex(irq_re)
                                        if irq_threads:
                                                thread_list += irq_threads
                                                irq_list.remove(irq)

The given irqs from command-line are stored in irq_list variable. If
there is a relevant threaded irq of an IRQ, put the thread into
thread_list and remove the IRQ from irq_list. However, it
unintentionally makes skipping an element because an index in the for
statement has been already moved to a next element.

  64 eth0-0             0xffff  bnx2
  65 eth0-1               0xff  bnx2
  66 eth0-2             0xffff  bnx2
  67 eth0-3               0xff  bnx2
  68 eth0-4             0xffff  bnx2
  69 eth0-5               0xff  bnx2
  70 eth0-6             0xffff  bnx2
  71 eth0-7               0xff  bnx2

As a result, threads_list contains IRQ threads for 64, 66, 68, 70. The
rest of IRQs are remained in irq_list. So, CPU affinity only apply to
irq_list.

elif o in ("-m", "--move", "-x", "--spread"):
        if not cpu_list:
                print "tuna: --move " + _("requires a cpu list!")
                sys.exit(2)
        if not (thread_list or irq_list):
                print "tuna: --move " + _("requires a list of threads/irqs!")
                sys.exit(2)

        spread = o in ("-x", "--spread")
        if thread_list:
                tuna.move_threads_to_cpu(cpu_list, thread_list,
                                         spread = spread)

        if irq_list:
                tuna.move_irqs_to_cpu(cpu_list, irq_list,
                                      spread = spread)

move_irqs_to_cpu calls set_irq_affinity to set IRQ's CPU affinity on a
given IRQ.

In case of move_threads_to_cpu, it sets process's CPU affinity mask on a
given thread using schedutils.set_affinity which is a wrapper for
sched_setaffinity(2). But it doesn't generally set IRQ's CPU affinity.

So, I've proposed a patch which basically makes IRQs remaining in
irq_list.

Reported on BZ: 665483

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/tuna-cmd.py b/tuna-cmd.py
index aafd2e4..a3b0aff 100755
--- a/tuna-cmd.py
+++ b/tuna-cmd.py
@@ -552,8 +552,12 @@ def main():
 					irq_re = tuna.threaded_irq_re(irq)
 					irq_threads = ps.find_by_regex(irq_re)
 					if irq_threads:
+						# Change the affinity of the thread too
+						# as we can't rely on changing the irq
+						# affinity changing the affinity of the
+						# thread or vice versa. We need to change
+						# both.
 						thread_list += irq_threads
-						irq_list.remove(irq)
 
 		elif o in ("-U", "--no_uthreads"):
 			uthreads = False