linux-toradex.git/include/linux/vmstat.h, branch Colibri_T30_LinuxImageV2.1Beta2_20140206

atomic: use

2011-07-26T23:49:47+00:00

This allows us to move duplicated code in 
(atomic_inc_not_zero() for now) to 

Signed-off-by: Arun Sharma 
Reviewed-by: Eric Dumazet 
Cc: Ingo Molnar 
Cc: David Miller 
Cc: Eric Dumazet 
Acked-by: Mike Frysinger 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: move enum vm_event_item into a standalone header file

2011-05-27T00:12:34+00:00

enums are problematic because they cannot be forward-declared:

  akpm2:/home/akpm> cat t.c

  enum foo;

  static inline void bar(enum foo f)
  {
  }
  akpm2:/home/akpm> gcc -c t.c
  t.c:4: error: parameter 1 ('f') has incomplete type

So move the enum's definition into a standalone header file which can be used
wherever its definition is needed.

Cc: Ying Han 
Cc: KAMEZAWA Hiroyuki 
Cc: KOSAKI Motohiro 
Cc: Minchan Kim 
Cc: Daisuke Nishimura 
Cc: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, mem-hotplug: update pcp->stat_threshold when memory hotplug occur

2011-05-25T15:39:09+00:00

Currently, cpu hotplug updates pcp->stat_threshold, but memory hotplug
doesn't.  There is no reason for this.

[akpm@linux-foundation.org: fix CONFIG_SMP=n build]
Signed-off-by: KOSAKI Motohiro 
Reviewed-by: KAMEZAWA Hiroyuki 
Acked-by: Mel Gorman 
Acked-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: per-node vmstat: show proper vmstats

2011-05-25T15:39:07+00:00

commit 2ac390370a ("writeback: add
/sys/devices/system/node//vmstat") added vmstat entry.  But
strangely it only show nr_written and nr_dirtied.

        # cat /sys/devices/system/node/node20/vmstat
        nr_written 0
        nr_dirtied 0

Of course, It's not adequate.  With this patch, the vmstat show all vm
stastics as /proc/vmstat.

        # cat /sys/devices/system/node/node0/vmstat
	nr_free_pages 899224
	nr_inactive_anon 201
	nr_active_anon 17380
	nr_inactive_file 31572
	nr_active_file 28277
	nr_unevictable 0
	nr_mlock 0
	nr_anon_pages 17321
	nr_mapped 8640
	nr_file_pages 60107
	nr_dirty 33
	nr_writeback 0
	nr_slab_reclaimable 6850
	nr_slab_unreclaimable 7604
	nr_page_table_pages 3105
	nr_kernel_stack 175
	nr_unstable 0
	nr_bounce 0
	nr_vmscan_write 0
	nr_writeback_temp 0
	nr_isolated_anon 0
	nr_isolated_file 0
	nr_shmem 260
	nr_dirtied 1050
	nr_written 938
	numa_hit 962872
	numa_miss 0
	numa_foreign 0
	numa_interleave 8617
	numa_local 962872
	numa_other 0
	nr_anon_transparent_hugepages 0

[akpm@linux-foundation.org: no externs in .c files]
Signed-off-by: KOSAKI Motohiro 
Cc: Michael Rubin 
Cc: Wu Fengguang 
Acked-by: David Rientjes 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: add VM counters for transparent hugepages

2011-04-14T23:06:55+00:00

I found it difficult to make sense of transparent huge pages without
having any counters for its actions.  Add some counters to vmstat for
allocation of transparent hugepages and fallback to smaller pages.

Optional patch, but useful for development and understanding the system.

Contains improvements from Andrea Arcangeli and Johannes Weiner

[akpm@linux-foundation.org: coding-style fixes]
[hannes@cmpxchg.org: fix vmstat_text[] entries]
Signed-off-by: Andi Kleen 
Acked-by: Andrea Arcangeli 
Reviewed-by: KAMEZAWA Hiroyuki 
Signed-off-by: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: add __GFP_OTHER_NODE flag

2011-03-23T00:44:05+00:00

Add a new __GFP_OTHER_NODE flag to tell the low level numa statistics in
zone_statistics() that an allocation is on behalf of another thread.  This
way the local and remote counters can be still correct, even when
background daemons like khugepaged are changing memory mappings.

This only affects the accounting, but I think it's worth doing that right
to avoid confusing users.

I first tried to just pass down the right node, but this required a lot of
changes to pass down this parameter and at least one addition of a 10th
argument to a 9 argument function.  Using the flag is a lot less
intrusive.

Open: should be also used for migration?

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Andi Kleen 
Cc: Andrea Arcangeli 
Reviewed-by: KAMEZAWA Hiroyuki 
Cc: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: vmstat: use a single setter function and callback for adjusting percpu thresholds

2011-01-14T01:32:31+00:00

reduce_pgdat_percpu_threshold() and restore_pgdat_percpu_threshold() exist
to adjust the per-cpu vmstat thresholds while kswapd is awake to avoid
errors due to counter drift.  The functions duplicate some code so this
patch replaces them with a single set_pgdat_percpu_threshold() that takes
a callback function to calculate the desired threshold as a parameter.

[akpm@linux-foundation.org: readability tweak]
[kosaki.motohiro@jp.fujitsu.com: set_pgdat_percpu_threshold(): don't use for_each_online_cpu]
Signed-off-by: Mel Gorman 
Reviewed-by: Christoph Lameter 
Reviewed-by: KAMEZAWA Hiroyuki 
Signed-off-by: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: page allocator: adjust the per-cpu counter threshold when memory is low

2011-01-14T01:32:31+00:00

Commit aa45484 ("calculate a better estimate of NR_FREE_PAGES when memory
is low") noted that watermarks were based on the vmstat NR_FREE_PAGES.  To
avoid synchronization overhead, these counters are maintained on a per-cpu
basis and drained both periodically and when a threshold is above a
threshold.  On large CPU systems, the difference between the estimate and
real value of NR_FREE_PAGES can be very high.  The system can get into a
case where pages are allocated far below the min watermark potentially
causing livelock issues.  The commit solved the problem by taking a better
reading of NR_FREE_PAGES when memory was low.

Unfortately, as reported by Shaohua Li this accurate reading can consume a
large amount of CPU time on systems with many sockets due to cache line
bouncing.  This patch takes a different approach.  For large machines
where counter drift might be unsafe and while kswapd is awake, the per-cpu
thresholds for the target pgdat are reduced to limit the level of drift to
what should be a safe level.  This incurs a performance penalty in heavy
memory pressure by a factor that depends on the workload and the machine
but the machine should function correctly without accidentally exhausting
all memory on a node.  There is an additional cost when kswapd wakes and
sleeps but the event is not expected to be frequent - in Shaohua's test
case, there was one recorded sleep and wake event at least.

To ensure that kswapd wakes up, a safe version of zone_watermark_ok() is
introduced that takes a more accurate reading of NR_FREE_PAGES when called
from wakeup_kswapd, when deciding whether it is really safe to go back to
sleep in sleeping_prematurely() and when deciding if a zone is really
balanced or not in balance_pgdat().  We are still using an expensive
function but limiting how often it is called.

When the test case is reproduced, the time spent in the watermark
functions is reduced.  The following report is on the percentage of time
spent cumulatively spent in the functions zone_nr_free_pages(),
zone_watermark_ok(), __zone_watermark_ok(), zone_watermark_ok_safe(),
zone_page_state_snapshot(), zone_page_state().

vanilla                      11.6615%
disable-threshold            0.2584%

David said:

: We had to pull aa454840 "mm: page allocator: calculate a better estimate
: of NR_FREE_PAGES when memory is low and kswapd is awake" from 2.6.36
: internally because tests showed that it would cause the machine to stall
: as the result of heavy kswapd activity.  I merged it back with this fix as
: it is pending in the -mm tree and it solves the issue we were seeing, so I
: definitely think this should be pushed to -stable (and I would seriously
: consider it for 2.6.37 inclusion even at this late date).

Signed-off-by: Mel Gorman 
Reported-by: Shaohua Li 
Reviewed-by: Christoph Lameter 
Tested-by: Nicolas Bareil 
Cc: David Rientjes 
Cc: Kyle McMartin 
Cc: 		[2.6.37.1, 2.6.36.x]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: page allocator: calculate a better estimate of NR_FREE_PAGES when memory is low and kswapd is awake

2010-09-10T01:57:25+00:00

Ordinarily watermark checks are based on the vmstat NR_FREE_PAGES as it is
cheaper than scanning a number of lists.  To avoid synchronization
overhead, counter deltas are maintained on a per-cpu basis and drained
both periodically and when the delta is above a threshold.  On large CPU
systems, the difference between the estimated and real value of
NR_FREE_PAGES can be very high.  If NR_FREE_PAGES is much higher than
number of real free page in buddy, the VM can allocate pages below min
watermark, at worst reducing the real number of pages to zero.  Even if
the OOM killer kills some victim for freeing memory, it may not free
memory if the exit path requires a new page resulting in livelock.

This patch introduces a zone_page_state_snapshot() function (courtesy of
Christoph) that takes a slightly more accurate view of an arbitrary vmstat
counter.  It is used to read NR_FREE_PAGES while kswapd is awake to avoid
the watermark being accidentally broken.  The estimate is not perfect and
may result in cache line bounces but is expected to be lighter than the
IPI calls necessary to continually drain the per-cpu counters while kswapd
is awake.

Signed-off-by: Christoph Lameter 
Signed-off-by: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: compaction: direct compact when a high-order allocation fails

2010-05-25T15:06:59+00:00

Ordinarily when a high-order allocation fails, direct reclaim is entered
to free pages to satisfy the allocation.  With this patch, it is
determined if an allocation failed due to external fragmentation instead
of low memory and if so, the calling process will compact until a suitable
page is freed.  Compaction by moving pages in memory is considerably
cheaper than paging out to disk and works where there are locked pages or
no swap.  If compaction fails to free a page of a suitable size, then
reclaim will still occur.

Direct compaction returns as soon as possible.  As each block is
compacted, it is checked if a suitable page has been freed and if so, it
returns.

[akpm@linux-foundation.org: Fix build errors]
[aarcange@redhat.com: fix count_vm_event preempt in memory compaction direct reclaim]
Signed-off-by: Mel Gorman 
Acked-by: Rik van Riel 
Reviewed-by: Minchan Kim 
Cc: KOSAKI Motohiro 
Cc: Christoph Lameter 
Cc: KAMEZAWA Hiroyuki 
Signed-off-by: Andrea Arcangeli 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds