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  1. 10 11月, 2007 9 次提交
    • S
      sched: fix copy_namespace() <-> sched_fork() dependency in do_fork · 3c90e6e9
      由 Srivatsa Vaddagiri 提交于 
      Sukadev Bhattiprolu reported a kernel crash with control groups.
There are couple of problems discovered by Suka's test:

- The test requires the cgroup filesystem to be mounted with
  atleast the cpu and ns options (i.e both namespace and cpu 
  controllers are active in the same hierarchy). 

	# mkdir /dev/cpuctl
	# mount -t cgroup -ocpu,ns none cpuctl
	(or simply)
	# mount -t cgroup none cpuctl -> Will activate all controllers
					 in same hierarchy.

- The test invokes clone() with CLONE_NEWNS set. This causes a a new child
  to be created, also a new group (do_fork->copy_namespaces->ns_cgroup_clone->
  cgroup_clone) and the child is attached to the new group (cgroup_clone->
  attach_task->sched_move_task). At this point in time, the child's scheduler 
  related fields are uninitialized (including its on_rq field, which it has
  inherited from parent). As a result sched_move_task thinks its on
  runqueue, when it isn't.

  As a solution to this problem, I moved sched_fork() call, which
  initializes scheduler related fields on a new task, before
  copy_namespaces(). I am not sure though whether moving up will
  cause other side-effects. Do you see any issue?

- The second problem exposed by this test is that task_new_fair()
  assumes that parent and child will be part of the same group (which 
  needn't be as this test shows). As a result, cfs_rq->curr can be NULL
  for the child.

  The solution is to test for curr pointer being NULL in
  task_new_fair().

With the patch below, I could run ns_exec() fine w/o a crash.
Reported-by: NSukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: NSrivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      3c90e6e9
    • I
      sched: clean up the wakeup preempt check, #2 · 502d26b5
      由 Ingo Molnar 提交于 
      clean up the preemption check to not use unnecessary 64-bit
variables. This improves code size:

   text    data     bss     dec     hex filename
  44227    3326      36   47589    b9e5 sched.o.before
  44201    3326      36   47563    b9cb sched.o.after
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      502d26b5
    • I
      sched: clean up the wakeup preempt check · 77d9cc44
      由 Ingo Molnar 提交于 
      clean up the wakeup preemption check. No code changed:

   text    data     bss     dec     hex filename
  44227    3326      36   47589    b9e5 sched.o.before
  44227    3326      36   47589    b9e5 sched.o.after
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      77d9cc44
    • I
      sched: wakeup preemption fix · 8bc6767a
      由 Ingo Molnar 提交于 
      wakeup preemption fix: do not make it dependent on p->prio.
Preemption purely depends on ->vruntime.

This improves preemption in mixed-nice-level workloads.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      8bc6767a
    • I
      sched: remove PREEMPT_RESTRICT · 3e3e13f3
      由 Ingo Molnar 提交于 
      remove PREEMPT_RESTRICT. (this is a separate commit so that any
regression related to the removal itself is bisectable)
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      3e3e13f3
    • I
      sched: reintroduce SMP tunings again · 19978ca6
      由 Ingo Molnar 提交于 
      Yanmin Zhang reported an aim7 regression and bisected it down to:

 |  commit 38ad464d
 |  Author: Ingo Molnar <mingo@elte.hu>
 |  Date:   Mon Oct 15 17:00:02 2007 +0200
 |
 |     sched: uniform tunings
 |
 |     use the same defaults on both UP and SMP.

fix this by reintroducing similar SMP tunings again. This resolves
the regression.

(also update the comments to match the ilog2(nr_cpus) tuning effect)
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      19978ca6
    • P
      sched: reintroduce the sched_min_granularity tunable · b2be5e96
      由 Peter Zijlstra 提交于 
      we lost the sched_min_granularity tunable to a clever optimization
that uses the sched_latency/min_granularity ratio - but the ratio
is quite unintuitive to users and can also crash the kernel if the
ratio is set to 0. So reintroduce the min_granularity tunable,
while keeping the ratio maintained internally.

no functionality changed.

[ mingo@elte.hu: some fixlets. ]
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      b2be5e96
    • P
      sched: documentation: place_entity() comments · 2cb8600e
      由 Peter Zijlstra 提交于 
      Add a few comments to place_entity(). No code changed.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      2cb8600e
    • P
      sched: fix vslice · 10b77724
      由 Peter Zijlstra 提交于 
      vslice was missing a factor NICE_0_LOAD, as weight is in
weight*NICE_0_LOAD units.

the effect of this bug was larger initial slices and
thus latency-noisier forks.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      10b77724
  3. 30 10月, 2007 1 次提交
  5. 25 10月, 2007 2 次提交
    • P
      sched: isolate SMP balancing code a bit more · 681f3e68
      由 Peter Williams 提交于 
      At the moment, a lot of load balancing code that is irrelevant to non
SMP systems gets included during non SMP builds.

This patch addresses this issue and reduces the binary size on non
SMP systems:

   text    data     bss     dec     hex filename
  10983      28    1192   12203    2fab sched.o.before
  10739      28    1192   11959    2eb7 sched.o.after
Signed-off-by: NPeter Williams <pwil3058@bigpond.net.au>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      681f3e68
    • P
      sched: reduce balance-tasks overhead · e1d1484f
      由 Peter Williams 提交于 
      At the moment, balance_tasks() provides low level functionality for both
  move_tasks() and move_one_task() (indirectly) via the load_balance()
function (in the sched_class interface) which also provides dual
functionality.  This dual functionality complicates the interfaces and
internal mechanisms and makes the run time overhead of operations that
are called with two run queue locks held.

This patch addresses this issue and reduces the overhead of these
operations.
Signed-off-by: NPeter Williams <pwil3058@bigpond.net.au>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      e1d1484f
  7. 17 10月, 2007 1 次提交
  9. 15 10月, 2007 27 次提交