linux-toradex.git/include/linux/swap.h, branch v2.6.16.2

[PATCH] Terminate process that fails on a constrained allocation

2006-02-21T04:00:09+00:00

Some allocations are restricted to a limited set of nodes (due to memory
policies or cpuset constraints).  If the page allocator is not able to find
enough memory then that does not mean that overall system memory is low.

In particular going postal and more or less randomly shooting at processes
is not likely going to help the situation but may just lead to suicide (the
whole system coming down).

It is better to signal to the process that no memory exists given the
constraints that the process (or the configuration of the process) has
placed on the allocation behavior.  The process may be killed but then the
sysadmin or developer can investigate the situation.  The solution is
similar to what we do when running out of hugepages.

This patch adds a check before we kill processes.  At that point
performance considerations do not matter much so we just scan the zonelist
and reconstruct a list of nodes.  If the list of nodes does not contain all
online nodes then this is a constrained allocation and we should kill the
current process.

Signed-off-by: Christoph Lameter 
Cc: Nick Piggin 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Direct Migration V9: Avoid writeback / page_migrate() method

2006-02-01T16:53:17+00:00

Migrate a page with buffers without requiring writeback

This introduces a new address space operation migratepage() that may be used
by a filesystem to implement its own version of page migration.

A version is provided that migrates buffers attached to pages.  Some
filesystems (ext2, ext3, xfs) are modified to utilize this feature.

The swapper address space operation are modified so that a regular
migrate_page() will occur for anonymous pages without writeback (migrate_pages
forces every anonymous page to have a swap entry).

Signed-off-by: Mike Kravetz 
Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Direct Migration V9: remove_from_swap() to remove swap ptes

2006-02-01T16:53:16+00:00

Add remove_from_swap

remove_from_swap() allows the restoration of the pte entries that existed
before page migration occurred for anonymous pages by walking the reverse
maps.  This reduces swap use and establishes regular pte's without the need
for page faults.

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

[PATCH] Direct Migration V9: migrate_pages() extension

2006-02-01T16:53:16+00:00

Add direct migration support with fall back to swap.

Direct migration support on top of the swap based page migration facility.

This allows the direct migration of anonymous pages and the migration of file
backed pages by dropping the associated buffers (requires writeout).

Fall back to swap out if necessary.

The patch is based on lots of patches from the hotplug project but the code
was restructured, documented and simplified as much as possible.

Note that an additional patch that defines the migrate_page() method for
filesystems is necessary in order to avoid writeback for anonymous and file
backed pages.

Signed-off-by: KAMEZAWA Hiroyuki 
Signed-off-by: Mike Kravetz 
Signed-off-by: Christoph Lameter 
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] zone_reclaim: configurable off node allocation period.

2006-02-01T16:53:16+00:00

Currently the zone_reclaim code has a fixed window of 30 seconds of off node
allocations should a local zone have no unused pagecache pages left.  Reclaim
will be attempted again after this timeout period to avoid repeated useless
scans for memory.  This is also useful to established sufficiently large off
node allocation chunks to relieve the local node.

It may be beneficial to adjust that time period for some special situations.
For example if memory use was exceeding node capacity one may want to give up
for longer periods of time.  If memory spikes intermittendly then one may want
to shorten the time period to reduce the number of off node allocations.

This patch allows just that....

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

[PATCH] Zone reclaim: Reclaim logic

2006-01-19T03:20:17+00:00

Some bits for zone reclaim exists in 2.6.15 but they are not usable.  This
patch fixes them up, removes unused code and makes zone reclaim usable.

Zone reclaim allows the reclaiming of pages from a zone if the number of
free pages falls below the watermarks even if other zones still have enough
pages available.  Zone reclaim is of particular importance for NUMA
machines.  It can be more beneficial to reclaim a page than taking the
performance penalties that come with allocating a page on a remote zone.

Zone reclaim is enabled if the maximum distance to another node is higher
than RECLAIM_DISTANCE, which may be defined by an arch.  By default
RECLAIM_DISTANCE is 20.  20 is the distance to another node in the same
component (enclosure or motherboard) on IA64.  The meaning of the NUMA
distance information seems to vary by arch.

If zone reclaim is not successful then no further reclaim attempts will
occur for a certain time period (ZONE_RECLAIM_INTERVAL).

This patch was discussed before. See

http://marc.theaimsgroup.com/?l=linux-kernel&m=113519961504207&w=2
http://marc.theaimsgroup.com/?l=linux-kernel&m=113408418232531&w=2
http://marc.theaimsgroup.com/?l=linux-kernel&m=113389027420032&w=2
http://marc.theaimsgroup.com/?l=linux-kernel&m=113380938612205&w=2

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

[PATCH] mm: migration page refcounting fix

2006-01-19T03:20:17+00:00

Migration code currently does not take a reference to target page
properly, so between unlocking the pte and trying to take a new
reference to the page with isolate_lru_page, anything could happen to
it.

Fix this by holding the pte lock until we get a chance to elevate the
refcount.

Other small cleanups while we're here.

Signed-off-by: Nick Piggin 
Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Fix for CONFIG_NUMA without CONFIG_SWAP

2006-01-15T02:27:07+00:00

Some people apparently run CONFIG_NUMA without CONFIG_SWAP.  The migration
code currently depends on swap.  This patch provides a set of inline
fallback functions so that the kernel properly compiles.  However, calls to
migration functions will fail.

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

[PATCH] SwapMig: Extend parameters for migrate_pages()

2006-01-09T04:12:42+00:00

Extend the parameters of migrate_pages() to allow the caller control over the
fate of successfully migrated or impossible to migrate pages.

Swap migration and direct migration will have the same interface after this
patch so that patches can be independently applied to the policy layer and the
core migration code.

Signed-off-by: Christoph Lameter 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] SwapMig: add_to_swap() avoid atomic allocations

2006-01-09T04:12:42+00:00

Add gfp_mask to add_to_swap

add_to_swap does allocations with GFP_ATOMIC in order not to interfere with
swapping.  During migration we may have use add_to_swap extensively which may
lead to out of memory errors.

This patch makes add_to_swap take a parameter that specifies the gfp mask.
The page migration code can then make add_to_swap use GFP_KERNEL.

Signed-off-by: Hirokazu Takahashi 
Signed-off-by: Dave Hansen 
Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds