linux-toradex.git/include/linux/page-flags.h, branch v2.6.27.13

mm: rename page trylock

2008-08-05T04:31:34+00:00

Converting page lock to new locking bitops requires a change of page flag
operation naming, so we might as well convert it to something nicer
(!TestSetPageLocked_Lock => trylock_page, SetPageLocked => set_page_locked).

This also facilitates lockdeping of page lock.

Signed-off-by: Nick Piggin 
Acked-by: KOSAKI Motohiro 
Acked-by: Peter Zijlstra 
Acked-by: Andrew Morton 
Acked-by: Benjamin Herrenschmidt 
Signed-off-by: Linus Torvalds

[S390] Optimize storage key operations for anon pages

2008-08-01T14:39:30+00:00

For anonymous pages without a swap cache backing the check in
page_remove_rmap for the physical dirty bit in page_remove_rmap is
unnecessary. The instructions that are used to check and reset the dirty
bit are expensive. Removing the check noticably speeds up process exit.
In addition the clearing of the dirty bit in __SetPageUptodate is
pointless as well. With these two changes there is no storage key
operation for an anonymous page anymore if it does not hit the swap
space.

The micro benchmark which repeatedly executes an empty shell script
gets about 5% faster.

Signed-off-by: Martin Schwidefsky

slob: record page flag overlays explicitly

2008-07-24T17:47:15+00:00

SLOB reuses two page bits for internal purposes, it overlays PG_active and
PG_private.  This is hidden away in slob.c.  Document these overlays
explicitly in the main page-flags enum along with all the others.

Signed-off-by: Andy Whitcroft 
Cc: Pekka Enberg 
Cc: Christoph Lameter 
Cc: Matt Mackall 
Cc: Nick Piggin 
Reviewed-by: KOSAKI Motohiro 
Cc: KOSAKI Motohiro 
Cc: Rik van Riel 
Cc: Jeremy Fitzhardinge 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

slub: record page flag overlays explicitly

2008-07-24T17:47:15+00:00

SLUB reuses two page bits for internal purposes, it overlays PG_active and
PG_error.  This is hidden away in slub.c.  Document these overlays
explicitly in the main page-flags enum along with all the others.

Signed-off-by: Andy Whitcroft 
Cc: Pekka Enberg 
Cc: Christoph Lameter 
Cc: Matt Mackall 
Cc: Nick Piggin 
Tested-by: KOSAKI Motohiro 
Cc: KOSAKI Motohiro 
Cc: Rik van Riel 
Cc: Jeremy Fitzhardinge 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

page-flags: record page flag overlays explicitly

2008-07-24T17:47:15+00:00

With the recent page flag reorganisation we have a single enum which
defines the valid page flags and their values, nice and clear.  However
there are a number of bits which are overloaded by different subsystems.
Firstly there is PG_owner_priv_1 which is used by filesystems and by XEN.
Secondly both SLOB and SLUB use a couple of extra page bits to manage
internal state for pages they own; both overlay other bits.  All of these
"aliases" are scattered about the source making it very hard for a reader
to know if the bits are safe to rely on in all contexts; confusion here is
bad.

As we now have a single place where the bits are clearly assigned it makes
sense to clarify the reuse of bits by making the aliases explicit and
visible with the original bit assignments.  This patch creates explicit
aliases within the enum itself for the overloaded bits, creates standard
bit accessors PageFoo etc.  and uses those throughout.

This version pulls the bit manipulation out to standard named page bit
accessors as suggested by Christoph, it retains the explicit mapping to
the overlayed bits.  A fusion of both ideas.  This has been SLUB and SLOB
have been compile tested on x86_64 only, and SLUB boot tested.  If people
feel this is worth doing then I can run a fuller set of testing.

This patch:

Some page flags are used for more than one purpose, for example
PG_owner_priv_1.  Currently there are individual accessors for each user,
each built using the common flag name far away from the bit definitions.
This makes it hard to see all possible uses of these bits.

Now that we have a single enum to generate the bit orders it makes sense
to express overlays in the same place.  So create per use aliases for this
bit in the main page-flags enum and use those in the accessors.

[akpm@linux-foundation.org: fix xen]
Signed-off-by: Andy Whitcroft 
Cc: Pekka Enberg 
Cc: Christoph Lameter 
Cc: Matt Mackall 
Cc: Nick Piggin 
Cc: KAMEZAWA Hiroyuki 
Reviewed-by: KOSAKI Motohiro 
Cc: Rik van Riel 
Cc: Jeremy Fitzhardinge 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'linus' into x86/xen

2008-06-16T09:21:27+00:00

mm: Minor clean-up of page flags in mm/page_alloc.c

2008-06-09T17:22:24+00:00

Minor source code cleanup of page flags in mm/page_alloc.c.
Move the definition of the groups of bits to page-flags.h.

The purpose of this clean up is that the next patch will
conditionally add a page flag to the groups.  Doing that
in a header file is cleaner than adding #ifdefs to the
C code.

Signed-off-by: Russ Anderson 
Signed-off-by: Linus Torvalds

xen: implement save/restore

2008-05-27T08:11:38+00:00

This patch implements Xen save/restore and migration.

Saving is triggered via xenbus, which is polled in
drivers/xen/manage.c.  When a suspend request comes in, the kernel
prepares itself for saving by:

1 - Freeze all processes.  This is primarily to prevent any
    partially-completed pagetable updates from confusing the suspend
    process.  If CONFIG_PREEMPT isn't defined, then this isn't necessary.

2 - Suspend xenbus and other devices

3 - Stop_machine, to make sure all the other vcpus are quiescent.  The
    Xen tools require the domain to run its save off vcpu0.

4 - Within the stop_machine state, it pins any unpinned pgds (under
    construction or destruction), performs canonicalizes various other
    pieces of state (mostly converting mfns to pfns), and finally

5 - Suspend the domain

Restore reverses the steps used to save the domain, ending when all
the frozen processes are thawed.

Signed-off-by: Jeremy Fitzhardinge 
Signed-off-by: Thomas Gleixner

PAGEFLAGS_EXTENDED and separate page flags for Head and Tail

2008-04-28T15:58:22+00:00

Having separate page flags for the head and the tail of a compound page allows
the compiler to use bitops instead of operations on a word to check for a tail
page.  That is f.e.  important for virt_to_head_page() which is used in
various critical code paths (kfree for example):

Code for PageTail(page)

Before:

 mov    (%rdi),%rdx		page->flags
 mov    %rdx,%rax		3 bytes
 and    $0x12000,%eax		5 bytes
 cmp    $0x12000,%rax		6 bytes
 je     897 

After:

 mov    (%rdi),%rax
 test   $0x40,%ah			(3 bytes)
 jne    887 

So we go from 14 bytes to 3 bytes and from 3 instructions to one.  From the
use of 2 registers we go to none.

We can only use page flags for this if we have page flags available.  This
patch introduces CONFIG_PAGEFLAGS_EXTENDED that is set if pageflags are not
scarce due to SPARSEMEM using page flags for its sectionid on 32 bit NUMA
platforms.

Additional page flag definitions can be added to the CONFIG_PAGEFLAGS_EXTENDED
section in page-flags.h if the functionality depends on PAGEFLAGS_EXTENDED or
if more page flag overlapping tricks are used for the !PAGEFLAGS_EXTENDED
fallback (the upcoming virtual compound patch may hook in here and Rik's/Lee's
additional page flags to solve the reclaim issues could also be added there
[hint...  hint...  where are these patchsets?]).

Avoiding the overlaying of Pg_reclaim also clears the way for possible use of
compound pages for the pagecache or on the LRU.

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

page flags: add PAGEFLAGS_FALSE for flags that are always false

2008-04-28T15:58:22+00:00

Turns out that there are a number of times that a flag is simply always
returning 0.  Define a macro for that.

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