linux-toradex.git/fs/proc/stat.c, branch v3.3.1

sched/accounting, proc: Fix /proc/stat interrupts sum

2012-01-16T07:13:27+00:00

Commit 3292beb340c7688 ("sched/accounting: Change cpustat fields to an array")
deleted the code which provides us with the sum of all interrupts in the
system, causing vmstat to report zero interrupts occuring in the system.

Fix this by restoring the code.

Signed-off-by: Russell King 
Tested-by: Russell King  # [on ARM]
Tested-by: Tony Luck 
Tested-by: Steven Rostedt 
Cc: Glauber Costa 
Cc: KAMEZAWA Hiroyuki 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Paul Tuner 
Cc: Peter Zijlstra 
Signed-off-by: Ingo Molnar

Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-01-06T16:44:54+00:00

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits)
  sched/tracing: Add a new tracepoint for sleeptime
  sched: Disable scheduler warnings during oopses
  sched: Fix cgroup movement of waking process
  sched: Fix cgroup movement of newly created process
  sched: Fix cgroup movement of forking process
  sched: Remove cfs bandwidth period check in tg_set_cfs_period()
  sched: Fix load-balance lock-breaking
  sched: Replace all_pinned with a generic flags field
  sched: Only queue remote wakeups when crossing cache boundaries
  sched: Add missing rcu_dereference() around ->real_parent usage
  [S390] fix cputime overflow in uptime_proc_show
  [S390] cputime: add sparse checking and cleanup
  sched: Mark parent and real_parent as __rcu
  sched, nohz: Fix missing RCU read lock
  sched, nohz: Set the NOHZ_BALANCE_KICK flag for idle load balancer
  sched, nohz: Fix the idle cpu check in nohz_idle_balance
  sched: Use jump_labels for sched_feat
  sched/accounting: Fix parameter passing in task_group_account_field
  sched/accounting: Fix user/system tick double accounting
  sched/accounting: Re-use scheduler statistics for the root cgroup
  ...

Fix up conflicts in
 - arch/ia64/include/asm/cputime.h, include/asm-generic/cputime.h
	usecs_to_cputime64() vs the sparse cleanups
 - kernel/sched/fair.c, kernel/time/tick-sched.c
	scheduler changes in multiple branches

procfs: do not confuse jiffies with cputime64_t

2011-12-30T00:31:57+00:00

Commit 2a95ea6c0d129b4 ("procfs: do not overflow get_{idle,iowait}_time
for nohz") did not take into account that one some architectures jiffies
and cputime use different units.

This causes get_idle_time() to return numbers in the wrong units, making
the idle time fields in /proc/stat wrong.

Instead of converting the usec value returned by
get_cpu_{idle,iowait}_time_us to units of jiffies, use the new function
usecs_to_cputime64 to convert it to the correct unit of cputime64_t.

Signed-off-by: Andreas Schwab 
Acked-by: Michal Hocko 
Cc: Arnd Bergmann 
Cc: "Artem S. Tashkinov" 
Cc: Dave Jones 
Cc: Alexey Dobriyan 
Cc: Thomas Gleixner 
Cc: "Luck, Tony" 
Cc: Benjamin Herrenschmidt 
Cc: Martin Schwidefsky 
Cc: Heiko Carstens 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge commit 'v3.2-rc5' into sched/core

2011-12-15T07:21:30+00:00

Merge reason: Pick up the latest fixes.

Signed-off-by: Ingo Molnar

procfs: do not overflow get_{idle,iowait}_time for nohz

2011-12-09T15:50:29+00:00

Since commit a25cac5198d4 ("proc: Consider NO_HZ when printing idle and
iowait times") we are reporting idle/io_wait time also while a CPU is
tickless.  We rely on get_{idle,iowait}_time functions to retrieve
proper data.

These functions, however, use usecs_to_cputime to translate micro
seconds time to cputime64_t.  This is just an alias to usecs_to_jiffies
which reduces the data type from u64 to unsigned int and also checks
whether the given parameter overflows jiffies_to_usecs(MAX_JIFFY_OFFSET)
and returns MAX_JIFFY_OFFSET in that case.

When we overflow depends on CONFIG_HZ but especially for CONFIG_HZ_300
it is quite low (1431649781) so we are getting MAX_JIFFY_OFFSET for
>3000s! until we overflow unsigned int.  Just for reference
CONFIG_HZ_100 has an overflow window around 20s, CONFIG_HZ_250 ~8s and
CONFIG_HZ_1000 ~2s.

This results in a bug when people saw [h]top going mad reporting 100%
CPU usage even though there was basically no CPU load.  The reason was
simply that /proc/stat stopped reporting idle/io_wait changes (and
reported MAX_JIFFY_OFFSET) and so the only change happening was for user
system time.

Let's use nsecs_to_jiffies64 instead which doesn't reduce the precision
to 32b type and it is much more appropriate for cumulative time values
(unlike usecs_to_jiffies which intended for timeout calculations).

Signed-off-by: Michal Hocko 
Tested-by: Artem S. Tashkinov 
Cc: Dave Jones 
Cc: Arnd Bergmann 
Cc: Alexey Dobriyan 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sched/accounting: Change cpustat fields to an array

2011-12-06T08:06:38+00:00

This patch changes fields in cpustat from a structure, to an
u64 array. Math gets easier, and the code is more flexible.

Signed-off-by: Glauber Costa 
Reviewed-by: KAMEZAWA Hiroyuki 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Paul Tuner 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1322498719-2255-2-git-send-email-glommer@parallels.com
Signed-off-by: Ingo Molnar

proc: Consider NO_HZ when printing idle and iowait times

2011-09-08T09:10:55+00:00

show_stat handler of the /proc/stat file relies on kstat_cpu(cpu)
statistics when priting information about idle and iowait times.
This is OK if we are not using tickless kernel (CONFIG_NO_HZ) because
counters are updated periodically.
With NO_HZ things got more tricky because we are not doing idle/iowait
accounting while we are tickless so the value might get outdated.
Users of /proc/stat will notice that by unchanged idle/iowait values
which is then interpreted as 0% idle/iowait time. From the user space
POV this is an unexpected behavior and a change of the interface.

Let's fix this by using get_cpu_{idle,iowait}_time_us which accounts the
total idle/iowait time since boot and it doesn't rely on sampling or any
other periodic activity. Fall back to the previous behavior if NO_HZ is
disabled or not configured.

Signed-off-by: Michal Hocko 
Cc: Dave Jones 
Cc: Arnd Bergmann 
Cc: Alexey Dobriyan 
Link: http://lkml.kernel.org/r/39181366adac1b39cb6aa3cd53ff0f7c78d32676.1314172057.git.mhocko@suse.cz
Signed-off-by: Thomas Gleixner

proc/stat: use defined macro KMALLOC_MAX_SIZE

2011-05-27T00:12:37+00:00

There is a macro for the max size kmalloc can allocate, so use it instead
of a hardcoded number.

Signed-off-by: Yuanhan Liu 
Cc: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: use seq_puts()/seq_putc() where possible

2011-01-13T16:03:16+00:00

For string without format specifiers, use seq_puts().
For seq_printf("\n"), use seq_putc('\n').

   text	   data	    bss	    dec	    hex	filename
  61866	    488	    112	  62466	   f402	fs/proc/proc.o
  61729	    488	    112	  62329	   f379	fs/proc/proc.o
  ----------------------------------------------------
  			   -139

Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

/proc/stat: fix scalability of irq sum of all cpu

2010-10-28T01:03:13+00:00

In /proc/stat, the number of per-IRQ event is shown by making a sum each
irq's events on all cpus.  But we can make use of kstat_irqs().

kstat_irqs() do the same calculation, If !CONFIG_GENERIC_HARDIRQ,
it's not a big cost. (Both of the number of cpus and irqs are small.)

If a system is very big and CONFIG_GENERIC_HARDIRQ, it does

	for_each_irq()
		for_each_cpu()
			- look up a radix tree
			- read desc->irq_stat[cpu]
This seems not efficient. This patch adds kstat_irqs() for
CONFIG_GENRIC_HARDIRQ and change the calculation as

	for_each_irq()
		look up radix tree
		for_each_cpu()
			- read desc->irq_stat[cpu]

This reduces cost.

A test on (4096cpusp, 256 nodes, 4592 irqs) host (by Jack Steiner)

%time cat /proc/stat > /dev/null

Before Patch:	 2.459 sec
After Patch :	  .561 sec

[akpm@linux-foundation.org: unexport kstat_irqs, coding-style tweaks]
[akpm@linux-foundation.org: fix unused variable 'per_irq_sum']
Signed-off-by: KAMEZAWA Hiroyuki 
Tested-by: Jack Steiner 
Acked-by: Jack Steiner 
Cc: Yinghai Lu 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds