linux.git/mm/vmstat.c, branch v2.6.31

vmscan: count the number of times zone_reclaim() scans and fails

2009-06-17T02:47:46+00:00

On NUMA machines, the administrator can configure zone_reclaim_mode that
is a more targetted form of direct reclaim.  On machines with large NUMA
distances for example, a zone_reclaim_mode defaults to 1 meaning that
clean unmapped pages will be reclaimed if the zone watermarks are not
being met.

There is a heuristic that determines if the scan is worthwhile but it is
possible that the heuristic will fail and the CPU gets tied up scanning
uselessly.  Detecting the situation requires some guesswork and
experimentation so this patch adds a counter "zreclaim_failed" to
/proc/vmstat.  If during high CPU utilisation this counter is increasing
rapidly, then the resolution to the problem may be to set
/proc/sys/vm/zone_reclaim_mode to 0.

[akpm@linux-foundation.org: name things consistently]
Signed-off-by: Mel Gorman 
Reviewed-by: Rik van Riel 
Cc: Christoph Lameter 
Reviewed-by: KOSAKI Motohiro 
Cc: Wu Fengguang 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: remove CONFIG_UNEVICTABLE_LRU config option

2009-06-17T02:47:42+00:00

Currently, nobody wants to turn UNEVICTABLE_LRU off.  Thus this
configurability is unnecessary.

Signed-off-by: KOSAKI Motohiro 
Cc: Johannes Weiner 
Cc: Andi Kleen 
Acked-by: Minchan Kim 
Cc: David Woodhouse 
Cc: Matt Mackall 
Cc: Rik van Riel 
Cc: Lee Schermerhorn 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vmscan: don't export nr_saved_scan in /proc/zoneinfo

2009-06-17T02:47:39+00:00

The lru->nr_saved_scan's are not meaningful counters for even kernel
developers.  They typically are smaller than 32 and are always 0 for large
lists.  So remove them from /proc/zoneinfo.

Hopefully this interface change won't break too many scripts.
/proc/zoneinfo is too unstructured to be script friendly, and I wonder the
affected scripts - if there are any - are still bleeding since the not
long ago commit "vmscan: split LRU lists into anon & file sets", which
also touched the "scanned" line :)

If we are to re-export accumulated vmscan counts in the future, they can
go to new lines in /proc/zoneinfo instead of the current form, or to
/sys/devices/system/node/node0/meminfo?

Signed-off-by: Wu Fengguang 

Acked-by: Rik van Riel 
Cc: Nick Piggin 
Acked-by: Christoph Lameter 
Cc: Peter Zijlstra 
Cc: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vmscan: cleanup the scan batching code

2009-06-17T02:47:39+00:00

The vmscan batching logic is twisting.  Move it into a standalone function
nr_scan_try_batch() and document it.  No behavior change.

Signed-off-by: Wu Fengguang 
Acked-by: Rik van Riel 
Cc: Nick Piggin 
Cc: Christoph Lameter 
Acked-by: Peter Zijlstra 
Acked-by: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

page allocator: use allocation flags as an index to the zone watermark

2009-06-17T02:47:35+00:00

ALLOC_WMARK_MIN, ALLOC_WMARK_LOW and ALLOC_WMARK_HIGH determin whether
pages_min, pages_low or pages_high is used as the zone watermark when
allocating the pages.  Two branches in the allocator hotpath determine
which watermark to use.

This patch uses the flags as an array index into a watermark array that is
indexed with WMARK_* defines accessed via helpers.  All call sites that
use zone->pages_* are updated to use the helpers for accessing the values
and the array offsets for setting.

Signed-off-by: Mel Gorman 
Reviewed-by: Christoph Lameter 
Cc: KOSAKI Motohiro 
Cc: Pekka Enberg 
Cc: Peter Zijlstra 
Cc: Nick Piggin 
Cc: Dave Hansen 
Cc: Lee Schermerhorn 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[ARM] Double check memmap is actually valid with a memmap has unexpected holes V2

2009-05-18T10:22:24+00:00

pfn_valid() is meant to be able to tell if a given PFN has valid memmap
associated with it or not. In FLATMEM, it is expected that holes always
have valid memmap as long as there is valid PFNs either side of the hole.
In SPARSEMEM, it is assumed that a valid section has a memmap for the
entire section.

However, ARM and maybe other embedded architectures in the future free
memmap backing holes to save memory on the assumption the memmap is never
used. The page_zone linkages are then broken even though pfn_valid()
returns true. A walker of the full memmap must then do this additional
check to ensure the memmap they are looking at is sane by making sure the
zone and PFN linkages are still valid. This is expensive, but walkers of
the full memmap are extremely rare.

This was caught before for FLATMEM and hacked around but it hits again for
SPARSEMEM because the page_zone linkages can look ok where the PFN linkages
are totally screwed. This looks like a hatchet job but the reality is that
any clean solution would end up consumning all the memory saved by punching
these unexpected holes in the memmap. For example, we tried marking the
memmap within the section invalid but the section size exceeds the size of
the hole in most cases so pfn_valid() starts returning false where valid
memmap exists. Shrinking the size of the section would increase memory
consumption offsetting the gains.

This patch identifies when an architecture is punching unexpected holes
in the memmap that the memory model cannot automatically detect and sets
ARCH_HAS_HOLES_MEMORYMODEL. At the moment, this is restricted to EP93xx
which is the model sub-architecture this has been reported on but may expand
later. When set, walkers of the full memmap must call memmap_valid_within()
for each PFN and passing in what it expects the page and zone to be for
that PFN. If it finds the linkages to be broken, it assumes the memmap is
invalid for that PFN.

Signed-off-by: Mel Gorman 
Signed-off-by: Russell King

mm: align vmstat_work's timer

2009-04-03T02:04:48+00:00

Even though vmstat_work is marked deferrable, there are still benefits to
aligning it.  For certain applications we want to keep OS jitter as low as
possible and aligning timers and work so they occur together can reduce
their overall impact.

Signed-off-by: Anton Blanchard 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: introduce for_each_populated_zone() macro

2009-04-01T15:59:11+00:00

Impact: cleanup

In almost cases, for_each_zone() is used with populated_zone().  It's
because almost function doesn't need memoryless node information.
Therefore, for_each_populated_zone() can help to make code simplify.

This patch has no functional change.

[akpm@linux-foundation.org: small cleanup]
Signed-off-by: KOSAKI Motohiro 
Cc: KAMEZAWA Hiroyuki 
Cc: Mel Gorman 
Reviewed-by: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpumask: use new cpumask_ functions in core code.

2009-03-30T11:35:16+00:00

Impact: cleanup

Time to clean up remaining laggards using the old cpu_ functions.

Signed-off-by: Rusty Russell 
Cc: Greg Kroah-Hartman 
Cc: Ingo Molnar 
Cc: Trond.Myklebust@netapp.com

cpumask: convert mm/

2008-12-31T23:42:29+00:00

Impact: Use new API

Convert kernel mm functions to use struct cpumask.

We skip include/linux/percpu.h and mm/allocpercpu.c, which are in flux.

Signed-off-by: Rusty Russell 
Signed-off-by: Mike Travis 
Reviewed-by: Christoph Lameter