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  1. 10 4月, 2013 5 次提交
  3. 08 4月, 2013 1 次提交
  5. 18 3月, 2013 1 次提交
  7. 14 3月, 2013 2 次提交
    • A
      sched: Fix variable name misnomer, add comments · 1bf08230
      由 Andrei Epure 提交于 
      The min_vruntime variable actually stores the maximum value.
The added comment was taken from place_entity function.
Signed-off-by: NAndrei Epure <epure.andrei@gmail.com>
Cc: peterz@infradead.org
Link: http://lkml.kernel.org/r/1363115544-1964-1-git-send-email-epure.andrei@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      1bf08230
    • F
      sched: Lower chances of cputime scaling overflow · d9a3c982
      由 Frederic Weisbecker 提交于 
      Some users have reported that after running a process with
hundreds of threads on intensive CPU-bound loads, the cputime
of the group started to freeze after a few days.

This is due to how we scale the tick-based cputime against
the scheduler precise execution time value.

We add the values of all threads in the group and we multiply
that against the sum of the scheduler exec runtime of the whole
group.

This easily overflows after a few days/weeks of execution.

A proposed solution to solve this was to compute that multiplication
on stime instead of utime:
   62188451
   ("cputime: Avoid multiplication overflow on utime scaling")

The rationale behind that was that it's easy for a thread to
spend most of its time in userspace under intensive CPU-bound workload
but it's much harder to do CPU-bound intensive long run in the kernel.

This postulate got defeated when a user recently reported he was still
seeing cputime freezes after the above patch. The workload that
triggers this issue relates to intensive networking workloads where
most of the cputime is consumed in the kernel.

To reduce much more the opportunities for multiplication overflow,
lets reduce the multiplication factors to the remainders of the division
between sched exec runtime and cputime. Assuming the difference between
these shouldn't ever be that large, it could work on many situations.

This gets the same results as in the upstream scaling code except for
a small difference: the upstream code always rounds the results to
the nearest integer not greater to what would be the precise result.
The new code rounds to the nearest integer either greater or not
greater. In practice this difference probably shouldn't matter but
it's worth mentioning.

If this solution appears not to be enough in the end, we'll
need to partly revert back to the behaviour prior to commit
     0cf55e1e
     ("sched, cputime: Introduce thread_group_times()")

Back then, the scaling was done on exit() time before adding the cputime
of an exiting thread to the signal struct. And then we'll need to
scale one-by-one the live threads cputime in thread_group_cputime(). The
drawback may be a slightly slower code on exit time.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
      d9a3c982
  9. 11 3月, 2013 2 次提交
  11. 08 3月, 2013 2 次提交
    • F
      cputime: Dynamically scale cputime for full dynticks accounting · 9fbc42ea
      由 Frederic Weisbecker 提交于 
      The full dynticks cputime accounting is able to account either
using the tick or the context tracking subsystem. This way
the housekeeping CPU can keep the low overhead tick based
solution.

This latter mode has a low jiffies resolution granularity and
need to be scaled against CFS precise runtime accounting to
improve its result. We are doing this for CONFIG_TICK_CPU_ACCOUNTING,
now we also need to expand it to full dynticks accounting dynamic
off-case as well.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Mats Liljegren <mats.liljegren@enea.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      9fbc42ea
    • F
      context_tracking: Restore preempted context state after preempt_schedule_irq() · b22366cd
      由 Frederic Weisbecker 提交于 
      From the context tracking POV, preempt_schedule_irq() behaves pretty much
like an exception: It can be called anytime and schedule another task.

But currently it doesn't restore the context tracking state of the preempted
code on preempt_schedule_irq() return.

As a result, if preempt_schedule_irq() is called in the tiny frame between
user_enter() and the actual return to userspace, we resume userspace with
the wrong context tracking state.

Fix this by using exception_enter/exit() which are a perfect fit for this
kind of issue.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Mats Liljegren <mats.liljegren@enea.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      b22366cd
  13. 06 3月, 2013 7 次提交
  15. 28 2月, 2013 1 次提交
    • S
      hlist: drop the node parameter from iterators · b67bfe0d
      由 Sasha Levin 提交于 
      I'm not sure why, but the hlist for each entry iterators were conceived

        list_for_each_entry(pos, head, member)

The hlist ones were greedy and wanted an extra parameter:

        hlist_for_each_entry(tpos, pos, head, member)

Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.

Besides the semantic patch, there was some manual work required:

 - Fix up the actual hlist iterators in linux/list.h
 - Fix up the declaration of other iterators based on the hlist ones.
 - A very small amount of places were using the 'node' parameter, this
 was modified to use 'obj->member' instead.
 - Coccinelle didn't handle the hlist_for_each_entry_safe iterator
 properly, so those had to be fixed up manually.

The semantic patch which is mostly the work of Peter Senna Tschudin is here:

@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;

type T;
expression a,c,d,e;
identifier b;
statement S;
@@

-T b;
    <+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
    ...+>

[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: NPeter Senna Tschudin <peter.senna@gmail.com>
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NSasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b67bfe0d
  17. 24 2月, 2013 2 次提交
    • F
      cputime: Use local_clock() for full dynticks cputime accounting · 7f6575f1
      由 Frederic Weisbecker 提交于 
      Running the full dynticks cputime accounting with preemptible
kernel debugging trigger the following warning:

	[    4.488303] BUG: using smp_processor_id() in preemptible [00000000] code: init/1
	[    4.490971] caller is native_sched_clock+0x22/0x80
	[    4.493663] Pid: 1, comm: init Not tainted 3.8.0+ #13
	[    4.496376] Call Trace:
	[    4.498996]  [<ffffffff813410eb>] debug_smp_processor_id+0xdb/0xf0
	[    4.501716]  [<ffffffff8101e642>] native_sched_clock+0x22/0x80
	[    4.504434]  [<ffffffff8101db99>] sched_clock+0x9/0x10
	[    4.507185]  [<ffffffff81096ccd>] fetch_task_cputime+0xad/0x120
	[    4.509916]  [<ffffffff81096dd5>] task_cputime+0x35/0x60
	[    4.512622]  [<ffffffff810f146e>] acct_update_integrals+0x1e/0x40
	[    4.515372]  [<ffffffff8117d2cf>] do_execve_common+0x4ff/0x5c0
	[    4.518117]  [<ffffffff8117cf14>] ? do_execve_common+0x144/0x5c0
	[    4.520844]  [<ffffffff81867a10>] ? rest_init+0x160/0x160
	[    4.523554]  [<ffffffff8117d457>] do_execve+0x37/0x40
	[    4.526276]  [<ffffffff810021a3>] run_init_process+0x23/0x30
	[    4.528953]  [<ffffffff81867aac>] kernel_init+0x9c/0xf0
	[    4.531608]  [<ffffffff8188356c>] ret_from_fork+0x7c/0xb0

We use sched_clock() to perform and fixup the cputime
accounting. However we are calling it with preemption enabled
from the read side, which trigger the bug above.

To fix this up, use local_clock() instead. It takes care of
preemption and also provide a more reliable clock source. This
is welcome for this kind of statistic that is widely relied on
in userspace.
Reported-by: NThomas Gleixner <tglx@linutronix.de>
Reported-by: NIngo Molnar <mingo@kernel.org>
Suggested-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1361636925-22288-3-git-send-email-fweisbec@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      7f6575f1
    • T
      sched: do not use cpu_to_node() to find an offlined cpu's node. · aa00d89c
      由 Tang Chen 提交于 
      If a cpu is offline, its nid will be set to -1, and cpu_to_node(cpu)
will return -1.  As a result, cpumask_of_node(nid) will return NULL.  In
this case, find_next_bit() in for_each_cpu will get a NULL pointer and
cause panic.

Here is a call trace:
  Call Trace:
   <IRQ>
    select_fallback_rq+0x71/0x190
    try_to_wake_up+0x2cb/0x2f0
    wake_up_process+0x15/0x20
    hrtimer_wakeup+0x22/0x30
    __run_hrtimer+0x83/0x320
    hrtimer_interrupt+0x106/0x280
    smp_apic_timer_interrupt+0x69/0x99
    apic_timer_interrupt+0x6f/0x80

There is a hrtimer process sleeping, whose cpu has already been
offlined.  When it is waken up, it tries to find another cpu to run, and
get a -1 nid.  As a result, cpumask_of_node(-1) returns NULL, and causes
ernel panic.

This patch fixes this problem by judging if the nid is -1.  If nid is
not -1, a cpu on the same node will be picked.  Else, a online cpu on
another node will be picked.
Signed-off-by: NTang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: NWen Congyang <wency@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      aa00d89c
  19. 22 2月, 2013 2 次提交
  21. 20 2月, 2013 1 次提交
  23. 19 2月, 2013 1 次提交
  25. 15 2月, 2013 1 次提交
  27. 08 2月, 2013 3 次提交
  29. 05 2月, 2013 2 次提交
  31. 04 2月, 2013 1 次提交
  33. 31 1月, 2013 1 次提交
  35. 29 1月, 2013 1 次提交
  37. 28 1月, 2013 4 次提交
    • F
      cputime: Safely read cputime of full dynticks CPUs · 6a61671b
      由 Frederic Weisbecker 提交于 
      While remotely reading the cputime of a task running in a
full dynticks CPU, the values stored in utime/stime fields
of struct task_struct may be stale. Its values may be those
of the last kernel <-> user transition time snapshot and
we need to add the tickless time spent since this snapshot.

To fix this, flush the cputime of the dynticks CPUs on
kernel <-> user transition and record the time / context
where we did this. Then on top of this snapshot and the current
time, perform the fixup on the reader side from task_times()
accessors.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
[fixed kvm module related build errors]
Signed-off-by: NSedat Dilek <sedat.dilek@gmail.com>
      6a61671b
    • F
      kvm: Prepare to add generic guest entry/exit callbacks · c11f11fc
      由 Frederic Weisbecker 提交于 
      Do some ground preparatory work before adding guest_enter()
and guest_exit() context tracking callbacks. Those will
be later used to read the guest cputime safely when we
run in full dynticks mode.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
      c11f11fc
    • F
      cputime: Use accessors to read task cputime stats · 6fac4829
      由 Frederic Weisbecker 提交于 
      This is in preparation for the full dynticks feature. While
remotely reading the cputime of a task running in a full
dynticks CPU, we'll need to do some extra-computation. This
way we can account the time it spent tickless in userspace
since its last cputime snapshot.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
      6fac4829
    • F
      cputime: Allow dynamic switch between tick/virtual based cputime accounting · 3f4724ea
      由 Frederic Weisbecker 提交于 
      Allow to dynamically switch between tick and virtual based
cputime accounting. This way we can provide a kind of "on-demand"
virtual based cputime accounting. In this mode, the kernel relies
on the context tracking subsystem to dynamically probe on kernel
boundaries.

This is in preparation for being able to stop the timer tick in
more places than just the idle state. Doing so will depend on
CONFIG_VIRT_CPU_ACCOUNTING_GEN which makes it possible to account
the cputime without the tick by hooking on kernel/user boundaries.

Depending whether the tick is stopped or not, we can switch between
tick and vtime based accounting anytime in order to minimize the
overhead associated to user hooks.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
      3f4724ea