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  1. 11 1月, 2012 9 次提交
    • J
      mm: try to distribute dirty pages fairly across zones · a756cf59
      由 Johannes Weiner 提交于 
      The maximum number of dirty pages that exist in the system at any time is
determined by a number of pages considered dirtyable and a user-configured
percentage of those, or an absolute number in bytes.

This number of dirtyable pages is the sum of memory provided by all the
zones in the system minus their lowmem reserves and high watermarks, so
that the system can retain a healthy number of free pages without having
to reclaim dirty pages.

But there is a flaw in that we have a zoned page allocator which does not
care about the global state but rather the state of individual memory
zones.  And right now there is nothing that prevents one zone from filling
up with dirty pages while other zones are spared, which frequently leads
to situations where kswapd, in order to restore the watermark of free
pages, does indeed have to write pages from that zone's LRU list.  This
can interfere so badly with IO from the flusher threads that major
filesystems (btrfs, xfs, ext4) mostly ignore write requests from reclaim
already, taking away the VM's only possibility to keep such a zone
balanced, aside from hoping the flushers will soon clean pages from that
zone.

Enter per-zone dirty limits.  They are to a zone's dirtyable memory what
the global limit is to the global amount of dirtyable memory, and try to
make sure that no single zone receives more than its fair share of the
globally allowed dirty pages in the first place.  As the number of pages
considered dirtyable excludes the zones' lowmem reserves and high
watermarks, the maximum number of dirty pages in a zone is such that the
zone can always be balanced without requiring page cleaning.

As this is a placement decision in the page allocator and pages are
dirtied only after the allocation, this patch allows allocators to pass
__GFP_WRITE when they know in advance that the page will be written to and
become dirty soon.  The page allocator will then attempt to allocate from
the first zone of the zonelist - which on NUMA is determined by the task's
NUMA memory policy - that has not exceeded its dirty limit.

At first glance, it would appear that the diversion to lower zones can
increase pressure on them, but this is not the case.  With a full high
zone, allocations will be diverted to lower zones eventually, so it is
more of a shift in timing of the lower zone allocations.  Workloads that
previously could fit their dirty pages completely in the higher zone may
be forced to allocate from lower zones, but the amount of pages that
"spill over" are limited themselves by the lower zones' dirty constraints,
and thus unlikely to become a problem.

For now, the problem of unfair dirty page distribution remains for NUMA
configurations where the zones allowed for allocation are in sum not big
enough to trigger the global dirty limits, wake up the flusher threads and
remedy the situation.  Because of this, an allocation that could not
succeed on any of the considered zones is allowed to ignore the dirty
limits before going into direct reclaim or even failing the allocation,
until a future patch changes the global dirty throttling and flusher
thread activation so that they take individual zone states into account.

			Test results

15M DMA + 3246M DMA32 + 504 Normal = 3765M memory
40% dirty ratio
16G USB thumb drive
10 runs of dd if=/dev/zero of=disk/zeroes bs=32k count=$((10 << 15))

		seconds			nr_vmscan_write
		        (stddev)	       min|     median|        max
xfs
vanilla:	 549.747( 3.492)	     0.000|      0.000|      0.000
patched:	 550.996( 3.802)	     0.000|      0.000|      0.000

fuse-ntfs
vanilla:	1183.094(53.178)	 54349.000|  59341.000|  65163.000
patched:	 558.049(17.914)	     0.000|      0.000|     43.000

btrfs
vanilla:	 573.679(14.015)	156657.000| 460178.000| 606926.000
patched:	 563.365(11.368)	     0.000|      0.000|   1362.000

ext4
vanilla:	 561.197(15.782)	     0.000|2725438.000|4143837.000
patched:	 568.806(17.496)	     0.000|      0.000|      0.000
Signed-off-by: NJohannes Weiner <jweiner@redhat.com>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Reviewed-by: NMichal Hocko <mhocko@suse.cz>
Tested-by: NWu Fengguang <fengguang.wu@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Chris Mason <chris.mason@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      a756cf59
    • J
      mm: exclude reserved pages from dirtyable memory · ab8fabd4
      由 Johannes Weiner 提交于 
      Per-zone dirty limits try to distribute page cache pages allocated for
writing across zones in proportion to the individual zone sizes, to reduce
the likelihood of reclaim having to write back individual pages from the
LRU lists in order to make progress.

This patch:

The amount of dirtyable pages should not include the full number of free
pages: there is a number of reserved pages that the page allocator and
kswapd always try to keep free.

The closer (reclaimable pages - dirty pages) is to the number of reserved
pages, the more likely it becomes for reclaim to run into dirty pages:

       +----------+ ---
       |   anon   |  |
       +----------+  |
       |          |  |
       |          |  -- dirty limit new    -- flusher new
       |   file   |  |                     |
       |          |  |                     |
       |          |  -- dirty limit old    -- flusher old
       |          |                        |
       +----------+                       --- reclaim
       | reserved |
       +----------+
       |  kernel  |
       +----------+

This patch introduces a per-zone dirty reserve that takes both the lowmem
reserve as well as the high watermark of the zone into account, and a
global sum of those per-zone values that is subtracted from the global
amount of dirtyable pages.  The lowmem reserve is unavailable to page
cache allocations and kswapd tries to keep the high watermark free.  We
don't want to end up in a situation where reclaim has to clean pages in
order to balance zones.

Not treating reserved pages as dirtyable on a global level is only a
conceptual fix.  In reality, dirty pages are not distributed equally
across zones and reclaim runs into dirty pages on a regular basis.

But it is important to get this right before tackling the problem on a
per-zone level, where the distance between reclaim and the dirty pages is
mostly much smaller in absolute numbers.

[akpm@linux-foundation.org: fix highmem build]
Signed-off-by: NJohannes Weiner <jweiner@redhat.com>
Reviewed-by: NRik van Riel <riel@redhat.com>
Reviewed-by: NMichal Hocko <mhocko@suse.cz>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Chris Mason <chris.mason@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ab8fabd4
    • D
      mm, debug: test for online nid when allocating on single node · f6d7e0cb
      由 David Rientjes 提交于 
      Calling alloc_pages_exact_node() means the allocation only passes the
zonelist of a single node into the page allocator.  If that node isn't
online, it's zonelist may never have been initialized causing a strange
oops that may not immediately be clear.

I recently debugged an issue where node 0 wasn't online and an allocator
was passing 0 to alloc_pages_exact_node() and it resulted in a NULL
pointer on zonelist->_zoneref.  If CONFIG_DEBUG_VM is enabled, though, it
would be nice to catch this a bit earlier.
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NMel Gorman <mgorman@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f6d7e0cb
    • S
      mm: more intensive memory corruption debugging · c0a32fc5
      由 Stanislaw Gruszka 提交于 
      With CONFIG_DEBUG_PAGEALLOC configured, the CPU will generate an exception
on access (read,write) to an unallocated page, which permits us to catch
code which corrupts memory.  However the kernel is trying to maximise
memory usage, hence there are usually few free pages in the system and
buggy code usually corrupts some crucial data.

This patch changes the buddy allocator to keep more free/protected pages
and to interlace free/protected and allocated pages to increase the
probability of catching corruption.

When the kernel is compiled with CONFIG_DEBUG_PAGEALLOC,
debug_guardpage_minorder defines the minimum order used by the page
allocator to grant a request.  The requested size will be returned with
the remaining pages used as guard pages.

The default value of debug_guardpage_minorder is zero: no change from
current behaviour.

[akpm@linux-foundation.org: tweak documentation, s/flg/flag/]
Signed-off-by: NStanislaw Gruszka <sgruszka@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c0a32fc5
    • D
      kernel.h: add BUILD_BUG() macro · 1399ff86
      由 David Daney 提交于 
      We can place this in definitions that we expect the compiler to remove by
dead code elimination.  If this assertion fails, we get a nice error
message at build time.

The GCC function attribute error("message") was added in version 4.3, so
we define a new macro __linktime_error(message) to expand to this for
GCC-4.3 and later.  This will give us an error diagnostic from the
compiler on the line that fails.  For other compilers
__linktime_error(message) expands to nothing, and we have to be content
with a link time error, but at least we will still get a build error.

BUILD_BUG() expands to the undefined function __build_bug_failed() and
will fail at link time if the compiler ever emits code for it.  On GCC-4.3
and later, attribute((error())) is used so that the failure will be noted
at compile time instead.
Signed-off-by: NDavid Daney <david.daney@cavium.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: DM <dm.n9107@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Acked-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1399ff86
    • M
      mm: avoid livelock on !__GFP_FS allocations · f90ac398
      由 Mel Gorman 提交于 
      Colin Cross reported;

  Under the following conditions, __alloc_pages_slowpath can loop forever:
  gfp_mask & __GFP_WAIT is true
  gfp_mask & __GFP_FS is false
  reclaim and compaction make no progress
  order <= PAGE_ALLOC_COSTLY_ORDER

  These conditions happen very often during suspend and resume,
  when pm_restrict_gfp_mask() effectively converts all GFP_KERNEL
  allocations into __GFP_WAIT.

  The oom killer is not run because gfp_mask & __GFP_FS is false,
  but should_alloc_retry will always return true when order is less
  than PAGE_ALLOC_COSTLY_ORDER.

In his fix, he avoided retrying the allocation if reclaim made no progress
and __GFP_FS was not set.  The problem is that this would result in
GFP_NOIO allocations failing that previously succeeded which would be very
unfortunate.

The big difference between GFP_NOIO and suspend converting GFP_KERNEL to
behave like GFP_NOIO is that normally flushers will be cleaning pages and
kswapd reclaims pages allowing GFP_NOIO to succeed after a short delay.
The same does not necessarily apply during suspend as the storage device
may be suspended.

This patch special cases the suspend case to fail the page allocation if
reclaim cannot make progress and adds some documentation on how
gfp_allowed_mask is currently used.  Failing allocations like this may
cause suspend to abort but that is better than a livelock.

[mgorman@suse.de: Rework fix to be suspend specific]
[rientjes@google.com: Move suspended device check to should_alloc_retry]
Reported-by: NColin Cross <ccross@android.com>
Signed-off-by: NMel Gorman <mgorman@suse.de>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f90ac398
    • K
      mm: remove unused pagevec_free · da066ad3
      由 Konstantin Khlebnikov 提交于 
      It not exported and now nobody uses it.
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Acked-by: NHugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      da066ad3
    • K
      mm: add free_hot_cold_page_list() helper · cc59850e
      由 Konstantin Khlebnikov 提交于 
      This patch adds helper free_hot_cold_page_list() to free list of 0-order
pages.  It frees pages directly from list without temporary page-vector.
It also calls trace_mm_pagevec_free() to simulate pagevec_free()
behaviour.

bloat-o-meter:

add/remove: 1/1 grow/shrink: 1/3 up/down: 267/-295 (-28)
function                                     old     new   delta
free_hot_cold_page_list                        -     264    +264
get_page_from_freelist                      2129    2132      +3
__pagevec_free                               243     239      -4
split_free_page                              380     373      -7
release_pages                                606     510     -96
free_page_list                               188       -    -188
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: NMinchan Kim <minchan.kim@gmail.com>
Acked-by: NHugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      cc59850e
    • J
      mm/page-writeback.c: make determine_dirtyable_memory static again · 1edf2234
      由 Johannes Weiner 提交于 
      The tracing ring-buffer used this function briefly, but not anymore.
Make it local to the writeback code again.

Also, move the function so that no forward declaration needs to be
reintroduced.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMel Gorman <mgorman@suse.de>
Reviewed-by: NMichal Hocko <mhocko@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1edf2234
  3. 10 1月, 2012 4 次提交
  5. 09 1月, 2012 1 次提交
    • J
      jbd: Remove j_barrier mutex · 00482785
      由 Jan Kara 提交于 
      j_barrier mutex is used for serializing different journal lock operations.  The
problem with it is that e.g. FIFREEZE ioctl results in process leaving kernel
with j_barrier mutex held which makes lockdep freak out. Also hibernation code
wants to freeze filesystem but it cannot do so because it then cannot hibernate
the system because of mutex being locked.

So we remove j_barrier mutex and use direct wait on j_barrier_count instead.
Since locking journal is a rare operation we don't have to care about fairness
or such things.

CC: Andrew Morton <akpm@linux-foundation.org>
Acked-by: NJoel Becker <jlbec@evilplan.org>
Signed-off-by: NJan Kara <jack@suse.cz>
      00482785
  7. 07 1月, 2012 10 次提交
  9. 06 1月, 2012 4 次提交
    • S
      dma-buf: Introduce dma buffer sharing mechanism · d15bd7ee
      由 Sumit Semwal 提交于 
      This is the first step in defining a dma buffer sharing mechanism.

A new buffer object dma_buf is added, with operations and API to allow easy
sharing of this buffer object across devices.

The framework allows:
- creation of a buffer object, its association with a file pointer, and
   associated allocator-defined operations on that buffer. This operation is
   called the 'export' operation.
- different devices to 'attach' themselves to this exported buffer object, to
  facilitate backing storage negotiation, using dma_buf_attach() API.
- the exported buffer object to be shared with the other entity by asking for
   its 'file-descriptor (fd)', and sharing the fd across.
- a received fd to get the buffer object back, where it can be accessed using
   the associated exporter-defined operations.
- the exporter and user to share the scatterlist associated with this buffer
   object using map_dma_buf and unmap_dma_buf operations.

Atleast one 'attach()' call is required to be made prior to calling the
map_dma_buf() operation.

Couple of building blocks in map_dma_buf() are added to ease introduction
of sync'ing across exporter and users, and late allocation by the exporter.

For this first version, this framework will work with certain conditions:
- *ONLY* exporter will be allowed to mmap to userspace (outside of this
   framework - mmap is not a buffer object operation),
- currently, *ONLY* users that do not need CPU access to the buffer are
   allowed.

More details are there in the documentation patch.

This is based on design suggestions from many people at the mini-summits[1],
most notably from Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
Daniel Vetter <daniel@ffwll.ch>.

The implementation is inspired from proof-of-concept patch-set from
Tomasz Stanislawski <t.stanislaws@samsung.com>, who demonstrated buffer sharing
between two v4l2 devices. [2]

[1]: https://wiki.linaro.org/OfficeofCTO/MemoryManagement
[2]: http://lwn.net/Articles/454389Signed-off-by: NSumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: NSumit Semwal <sumit.semwal@ti.com>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: NDave Airlie <airlied@redhat.com>
Reviewed-and-Tested-by: NRob Clark <rob.clark@linaro.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>
      d15bd7ee
    • I
      net: pack skb_shared_info more efficiently · 9f42f126
      由 Ian Campbell 提交于 
      nr_frags can be 8 bits since 256 is plenty of fragments. This allows it to be
packed with tx_flags.

Also by moving ip6_frag_id and dataref (both 4 bytes) next to each other we can
avoid a hole between ip6_frag_id and frag_list on 64 bit systems.
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      9f42f126
    • E
      net_sched: sfq: extend limits · 18cb8098
      由 Eric Dumazet 提交于 
      SFQ as implemented in Linux is very limited, with at most 127 flows
and limit of 127 packets. [ So if 127 flows are active, we have one
packet per flow ]

This patch brings to SFQ following features to cope with modern needs.

- Ability to specify a smaller per flow limit of inflight packets.
    (default value being at 127 packets)

- Ability to have up to 65408 active flows (instead of 127)

- Ability to have head drops instead of tail drops
  (to drop old packets from a flow)

Example of use : No more than 20 packets per flow, max 8000 flows, max
20000 packets in SFQ qdisc, hash table of 65536 slots.

tc qdisc add ... sfq \
        flows 8000 \
        depth 20 \
        headdrop \
        limit 20000 \
	divisor 65536

Ram usage :

2 bytes per hash table entry (instead of previous 1 byte/entry)
32 bytes per flow on 64bit arches, instead of 384 for QFQ, so much
better cache hit ratio.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
CC: Dave Taht <dave.taht@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      18cb8098
    • N
      netdev: FCoE: Add new ndo_get_fcoe_hbainfo() call · 68bad94e
      由 Neerav Parikh 提交于 
      This adds a new ndo_get_fcoe_hbainfo() call in
net_device_ops for FCoE protocol stack.

If supported by the underlying device, the FCoE protocol
stack will call this to get device specific information
from the underlying device.
This information will then be utilized by the FCoE protocol
stack to register Fiber Channel HBA attributes with the
Fiber Channel Management Service via Fabric Device
Management Interface (FDMI) as per the T11 FC-GS
specification.

Changes in v2:
- As per comments from David Miller aligning the parameters
of the ndo_get_fcoe_hbainfo()
Signed-off-by: NNeerav Parikh <Neerav.Parikh@intel.com>
Tested-by: NRoss Brattain <ross.b.brattain@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      68bad94e
  11. 05 1月, 2012 6 次提交
  13. 04 1月, 2012 6 次提交