linux.git/mm, branch v2.6.16

[PATCH] fix free swap cache latency

2006-03-17T15:51:26+00:00

Lee Revell reported 28ms latency when process with lots of swapped memory
exits.

2.6.15 introduced a latency regression when unmapping: in accounting the
zap_work latency breaker, pte_none counted 1, pte_present PAGE_SIZE, but a
swap entry counted nothing at all.  We think of pages present as the slow
case, but Lee's trace shows that free_swap_and_cache's radix tree lookup
can make a lot of work - and we could have been doing it many thousands of
times without a latency break.

Move the zap_work update up to account swap entries like pages present.
This does account non-linear pte_file entries, and unmap_mapping_range
skipping over swap entries, by the same amount even though they're quick:
but neither of those cases deserves complicating the code (and they're
treated no worse than they were in 2.6.14).

Signed-off-by: Hugh Dickins 
Acked-by: Nick Piggin 
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] fix race in pagevec_strip?

2006-03-17T15:51:25+00:00

We can call try_to_release_page() with PagePrivate off and a valid
page->mapping This may cause all sorts of trouble for the filesystem
*_releasepage() handlers.  XFS bombs out in that case.

Lock the page before checking for page private.

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

[PATCH] page migration: Fail with error if swap not setup

2006-03-17T15:51:25+00:00

Currently the migration of anonymous pages will silently fail if no swap is
setup.  This patch makes page migration functions check for available swap
and fail with -ENODEV if no swap space is available.

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

[PATCH] Consistent capabilites associated with MPOL_MOVE_ALL

2006-03-15T05:43:02+00:00

It seems that setting scheduling policy and priorities is also the kind of
thing that might be performed in apps that also use the NUMA API, so it
would seem consistent to use CAP_SYS_NICE for NUMA also.

So use CAP_SYS_NICE for controlling migration permissions.

Signed-off-by: Christoph Lameter 
Cc: Michael Kerrisk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] page migration: fail if page is in a vma flagged VM_LOCKED

2006-03-15T05:43:02+00:00

page migration currently simply retries a couple of times if try_to_unmap()
fails without inspecting the return code.

However, SWAP_FAIL indicates that the page is in a vma that has the
VM_LOCKED flag set (if ignore_refs ==1).  We can check for that return code
and avoid retrying the migration.

migrate_page_remove_references() now needs to return a reason why the
failure occured.  So switch migrate_page_remove_references to use -Exx
style error messages.

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

[PATCH] slab: Node rotor for freeing alien caches and remote per cpu pages.

2006-03-10T03:47:38+00:00

The cache reaper currently tries to free all alien caches and all remote
per cpu pages in each pass of cache_reap.  For a machines with large number
of nodes (such as Altix) this may lead to sporadic delays of around ~10ms.
Interrupts are disabled while reclaiming creating unacceptable delays.

This patch changes that behavior by adding a per cpu reap_node variable.
Instead of attempting to free all caches, we free only one alien cache and
the per cpu pages from one remote node.  That reduces the time spend in
cache_reap.  However, doing so will lengthen the time it takes to
completely drain all remote per cpu pagesets and all alien caches.  The
time needed will grow with the number of nodes in the system.  All caches
are drained when they overflow their respective capacity.  So the drawback
here is only that a bit of memory may be wasted for awhile longer.

Details:

1. Rename drain_remote_pages to drain_node_pages to allow the specification
   of the node to drain of pcp pages.

2. Add additional functions init_reap_node, next_reap_node for NUMA
   that manage a per cpu reap_node counter.

3. Add a reap_alien function that reaps only from the current reap_node.

For us this seems to be a critical issue.  Holdoffs of an average of ~7ms
cause some HPC benchmarks to slow down significantly.  F.e.  NAS parallel
slows down dramatically.  NAS parallel has a 12-16 seconds runtime w/o rotor
compared to 5.8 secs with the rotor patches.  It gets down to 5.05 secs with
the additional interrupt holdoff reductions.

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

[PATCH] memory hotadd: pgdat->node_present_pages fix

2006-03-10T03:47:38+00:00

When pages are onlined, not only zone->present_pages but also
pgdat->node_present_pages should be refreshed.

This parameter is used to show information at
/sys/device/system/node/nodeX/meminfo via si_meminfo_node().

So, it shows strange value for MemUsed which is calculated
(node_present_pages - all zones free pages).

Signed-off-by: Yasunori Goto 
Cc: Dave Hansen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] vmscan: no zone_reclaim if PF_MALLOC is set

2006-03-10T03:47:37+00:00

If the process has already set PF_MALLOC and is already using
current->reclaim_state then do not try to reclaim memory from the zone.
This is set by kswapd and/or synchrononous global reclaim which will not
take it lightly if we zap the reclaim_state.

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

[PATCH] page_add_file_rmap(): remove BUG_ON()s

2006-03-10T03:47:36+00:00

Remove two early-development BUG_ONs from page_add_file_rmap.

The pfn_valid test (originally useful for checking that nobody passed an
artificial struct page) comes too late, since we already have the struct
page.

The PageAnon test (useful when anon was first distinguished from file rmap)
prevents ->nopage implementations from reusing ->mapping, which would
otherwise be available.

Signed-off-by: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] slab: allocate larger cache_cache if order 0 fails

2006-03-08T22:15:04+00:00

kmem_cache_init() incorrectly assumes that the cache_cache object will fit
in an order 0 allocation.  On very large systems, this is not true.  Change
the code to try larger order allocations if order 0 fails.

Signed-off-by: Jack Steiner 
Cc: Manfred Spraul 
Cc: Pekka Enberg 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds