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  1. 10 12月, 2014 4 次提交
  3. 25 11月, 2014 3 次提交
  5. 29 10月, 2014 1 次提交
    • P
      rcu: Make rcu_barrier() understand about missing rcuo kthreads · d7e29933
      由 Paul E. McKenney 提交于 
      Commit 35ce7f29 (rcu: Create rcuo kthreads only for onlined CPUs)
avoids creating rcuo kthreads for CPUs that never come online.  This
fixes a bug in many instances of firmware: Instead of lying about their
age, these systems instead lie about the number of CPUs that they have.
Before commit 35ce7f29, this could result in huge numbers of useless
rcuo kthreads being created.

It appears that experience indicates that I should have told the
people suffering from this problem to fix their broken firmware, but
I instead produced what turned out to be a partial fix.   The missing
piece supplied by this commit makes sure that rcu_barrier() knows not to
post callbacks for no-CBs CPUs that have not yet come online, because
otherwise rcu_barrier() will hang on systems having firmware that lies
about the number of CPUs.

It is tempting to simply have rcu_barrier() refuse to post a callback on
any no-CBs CPU that does not have an rcuo kthread.  This unfortunately
does not work because rcu_barrier() is required to wait for all pending
callbacks.  It is therefore required to wait even for those callbacks
that cannot possibly be invoked.  Even if doing so hangs the system.

Given that posting a callback to a no-CBs CPU that does not yet have an
rcuo kthread can hang rcu_barrier(), It is tempting to report an error
in this case.  Unfortunately, this will result in false positives at
boot time, when it is perfectly legal to post callbacks to the boot CPU
before the scheduler has started, in other words, before it is legal
to invoke rcu_barrier().

So this commit instead has rcu_barrier() avoid posting callbacks to
CPUs having neither rcuo kthread nor pending callbacks, and has it
complain bitterly if it finds CPUs having no rcuo kthread but some
pending callbacks.  And when rcu_barrier() does find CPUs having no rcuo
kthread but pending callbacks, as noted earlier, it has no choice but
to hang indefinitely.
Reported-by: NYanko Kaneti <yaneti@declera.com>
Reported-by: NJay Vosburgh <jay.vosburgh@canonical.com>
Reported-by: NMeelis Roos <mroos@linux.ee>
Reported-by: NEric B Munson <emunson@akamai.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: NEric B Munson <emunson@akamai.com>
Tested-by: NJay Vosburgh <jay.vosburgh@canonical.com>
Tested-by: NYanko Kaneti <yaneti@declera.com>
Tested-by: NKevin Fenzi <kevin@scrye.com>
Tested-by: NMeelis Roos <mroos@linux.ee>
      d7e29933
  7. 08 10月, 2014 1 次提交
  9. 01 10月, 2014 2 次提交
  11. 25 9月, 2014 1 次提交
  13. 24 9月, 2014 1 次提交
  15. 18 9月, 2014 5 次提交
  17. 16 9月, 2014 1 次提交
    • Z
      kvm: ioapic: conditionally delay irq delivery duringeoi broadcast · 184564ef
      由 Zhang Haoyu 提交于 
      Currently, we call ioapic_service() immediately when we find the irq is still
active during eoi broadcast. But for real hardware, there's some delay between
the EOI writing and irq delivery.  If we do not emulate this behavior, and
re-inject the interrupt immediately after the guest sends an EOI and re-enables
interrupts, a guest might spend all its time in the ISR if it has a broken
handler for a level-triggered interrupt.

Such livelock actually happens with Windows guests when resuming from
hibernation.

As there's no way to recognize the broken handle from new raised ones, this patch
delays an interrupt if 10.000 consecutive EOIs found that the interrupt was
still high.  The guest can then make a little forward progress, until a proper
IRQ handler is set or until some detection routine in the guest (such as
Linux's note_interrupt()) recognizes the situation.

Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NZhang Haoyu <zhanghy@sangfor.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      184564ef
  19. 08 9月, 2014 1 次提交
  21. 06 9月, 2014 1 次提交
  23. 02 9月, 2014 2 次提交
    • Z
      ext4: track extent status tree shrinker delay statictics · eb68d0e2
      由 Zheng Liu 提交于 
      This commit adds some statictics in extent status tree shrinker.  The
purpose to add these is that we want to collect more details when we
encounter a stall caused by extent status tree shrinker.  Here we count
the following statictics:
  stats:
    the number of all objects on all extent status trees
    the number of reclaimable objects on lru list
    cache hits/misses
    the last sorted interval
    the number of inodes on lru list
  average:
    scan time for shrinking some objects
    the number of shrunk objects
  maximum:
    the inode that has max nr. of objects on lru list
    the maximum scan time for shrinking some objects

The output looks like below:
  $ cat /proc/fs/ext4/sda1/es_shrinker_info
  stats:
    28228 objects
    6341 reclaimable objects
    5281/631 cache hits/misses
    586 ms last sorted interval
    250 inodes on lru list
  average:
    153 us scan time
    128 shrunk objects
  maximum:
    255 inode (255 objects, 198 reclaimable)
    125723 us max scan time

If the lru list has never been sorted, the following line will not be
printed:
    586ms last sorted interval
If there is an empty lru list, the following lines also will not be
printed:
    250 inodes on lru list
  ...
  maximum:
    255 inode (255 objects, 198 reclaimable)
    0 us max scan time

Meanwhile in this commit a new trace point is defined to print some
details in __ext4_es_shrink().

Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jan Kara <jack@suse.cz>
Reviewed-by: NJan Kara <jack@suse.cz>
Signed-off-by: NZheng Liu <wenqing.lz@taobao.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      eb68d0e2
    • Z
      ext4: improve extents status tree trace point · e963bb1d
      由 Zheng Liu 提交于 
      This commit improves the trace point of extents status tree.  We rename
trace_ext4_es_shrink_enter in ext4_es_count() because it is also used
in ext4_es_scan() and we can not identify them from the result.

Further this commit fixes a variable name in trace point in order to
keep consistency with others.

Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jan Kara <jack@suse.cz>
Reviewed-by: NJan Kara <jack@suse.cz>
Signed-off-by: NZheng Liu <wenqing.lz@taobao.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
      e963bb1d
  25. 13 8月, 2014 1 次提交
  27. 08 8月, 2014 1 次提交
  29. 07 8月, 2014 2 次提交
    • M
      mm: pagemap: avoid unnecessary overhead when tracepoints are deactivated · 24b7e581
      由 Mel Gorman 提交于 
      This was formerly the series "Improve sequential read throughput" which
noted some major differences in performance of tiobench since 3.0.
While there are a number of factors, two that dominated were the
introduction of the fair zone allocation policy and changes to CFQ.

The behaviour of fair zone allocation policy makes more sense than
tiobench as a benchmark and CFQ defaults were not changed due to
insufficient benchmarking.

This series is what's left.  It's one functional fix to the fair zone
allocation policy when used on NUMA machines and a reduction of overhead
in general.  tiobench was used for the comparison despite its flaws as
an IO benchmark as in this case we are primarily interested in the
overhead of page allocator and page reclaim activity.

On UMA, it makes little difference to overhead

          3.16.0-rc3   3.16.0-rc3
             vanilla lowercost-v5
User          383.61      386.77
System        403.83      401.74
Elapsed      5411.50     5413.11

On a 4-socket NUMA machine it's a bit more noticable

          3.16.0-rc3   3.16.0-rc3
             vanilla lowercost-v5
User          746.94      802.00
System      65336.22    40852.33
Elapsed     27553.52    27368.46

This patch (of 6):

The LRU insertion and activate tracepoints take PFN as a parameter
forcing the overhead to the caller.  Move the overhead to the tracepoint
fast-assign method to ensure the cost is only incurred when the
tracepoint is active.
Signed-off-by: NMel Gorman <mgorman@suse.de>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      24b7e581
    • M
      mm tracing: tell mm_migrate_pages event about numa_misplaced · 4a262d26
      由 Max Asbock 提交于 
      The mm_migrate_pages trace event reports a reason for the migration,
typically as a symbolic string.  The exception is the reason
MR_NUMA_MISPLACED for which it just displays the numeric value:
mm_migrate_pages: nr_succeeded=1 nr_failed=0 mode=MIGRATE_ASYNC
reason=0x5

This patch makes the output consistent by introducing a string value for
MR_NUMA_MISPLACED.  The event is then reported as: mm_migrate_pages:
nr_succeeded=1 nr_failed=0 mode=MIGRATE_ASYNC reason=numa_misplaced
Signed-off-by: NMax Asbock <masbock@linux.vnet.ibm.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.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>
      4a262d26
  31. 06 8月, 2014 1 次提交
    • P
      KVM: Move more code under CONFIG_HAVE_KVM_IRQFD · c77dcacb
      由 Paolo Bonzini 提交于 
      Commits e4d57e1e (KVM: Move irq notifier implementation into
eventfd.c, 2014-06-30) included the irq notifier code unconditionally
in eventfd.c, while it was under CONFIG_HAVE_KVM_IRQCHIP before.

Similarly, commit 297e2105 (KVM: Give IRQFD its own separate enabling
Kconfig option, 2014-06-30) moved code from CONFIG_HAVE_IRQ_ROUTING
to CONFIG_HAVE_KVM_IRQFD but forgot to move the pieces that used to be
under CONFIG_HAVE_KVM_IRQCHIP.

Together, this broke compilation without CONFIG_KVM_XICS.  Fix by adding
or changing the #ifdefs so that they point at CONFIG_HAVE_KVM_IRQFD.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      c77dcacb
  33. 05 8月, 2014 2 次提交
  35. 02 8月, 2014 1 次提交
  37. 31 7月, 2014 2 次提交
  39. 29 7月, 2014 3 次提交
  41. 09 7月, 2014 1 次提交
    • M
      fence: dma-buf cross-device synchronization (v18) · e941759c
      由 Maarten Lankhorst 提交于 
      A fence can be attached to a buffer which is being filled or consumed
by hw, to allow userspace to pass the buffer without waiting to another
device.  For example, userspace can call page_flip ioctl to display the
next frame of graphics after kicking the GPU but while the GPU is still
rendering.  The display device sharing the buffer with the GPU would
attach a callback to get notified when the GPU's rendering-complete IRQ
fires, to update the scan-out address of the display, without having to
wake up userspace.

A driver must allocate a fence context for each execution ring that can
run in parallel. The function for this takes an argument with how many
contexts to allocate:
  + fence_context_alloc()

A fence is transient, one-shot deal.  It is allocated and attached
to one or more dma-buf's.  When the one that attached it is done, with
the pending operation, it can signal the fence:
  + fence_signal()

To have a rough approximation whether a fence is fired, call:
  + fence_is_signaled()

The dma-buf-mgr handles tracking, and waiting on, the fences associated
with a dma-buf.

The one pending on the fence can add an async callback:
  + fence_add_callback()

The callback can optionally be cancelled with:
  + fence_remove_callback()

To wait synchronously, optionally with a timeout:
  + fence_wait()
  + fence_wait_timeout()

When emitting a fence, call:
  + trace_fence_emit()

To annotate that a fence is blocking on another fence, call:
  + trace_fence_annotate_wait_on(fence, on_fence)

A default software-only implementation is provided, which can be used
by drivers attaching a fence to a buffer when they have no other means
for hw sync.  But a memory backed fence is also envisioned, because it
is common that GPU's can write to, or poll on some memory location for
synchronization.  For example:

  fence = custom_get_fence(...);
  if ((seqno_fence = to_seqno_fence(fence)) != NULL) {
    dma_buf *fence_buf = seqno_fence->sync_buf;
    get_dma_buf(fence_buf);

    ... tell the hw the memory location to wait ...
    custom_wait_on(fence_buf, seqno_fence->seqno_ofs, fence->seqno);
  } else {
    /* fall-back to sw sync * /
    fence_add_callback(fence, my_cb);
  }

On SoC platforms, if some other hw mechanism is provided for synchronizing
between IP blocks, it could be supported as an alternate implementation
with it's own fence ops in a similar way.

enable_signaling callback is used to provide sw signaling in case a cpu
waiter is requested or no compatible hardware signaling could be used.

The intention is to provide a userspace interface (presumably via eventfd)
later, to be used in conjunction with dma-buf's mmap support for sw access
to buffers (or for userspace apps that would prefer to do their own
synchronization).

v1: Original
v2: After discussion w/ danvet and mlankhorst on #dri-devel, we decided
    that dma-fence didn't need to care about the sw->hw signaling path
    (it can be handled same as sw->sw case), and therefore the fence->ops
    can be simplified and more handled in the core.  So remove the signal,
    add_callback, cancel_callback, and wait ops, and replace with a simple
    enable_signaling() op which can be used to inform a fence supporting
    hw->hw signaling that one or more devices which do not support hw
    signaling are waiting (and therefore it should enable an irq or do
    whatever is necessary in order that the CPU is notified when the
    fence is passed).
v3: Fix locking fail in attach_fence() and get_fence()
v4: Remove tie-in w/ dma-buf..  after discussion w/ danvet and mlankorst
    we decided that we need to be able to attach one fence to N dma-buf's,
    so using the list_head in dma-fence struct would be problematic.
v5: [ Maarten Lankhorst ] Updated for dma-bikeshed-fence and dma-buf-manager.
v6: [ Maarten Lankhorst ] I removed dma_fence_cancel_callback and some comments
    about checking if fence fired or not. This is broken by design.
    waitqueue_active during destruction is now fatal, since the signaller
    should be holding a reference in enable_signalling until it signalled
    the fence. Pass the original dma_fence_cb along, and call __remove_wait
    in the dma_fence_callback handler, so that no cleanup needs to be
    performed.
v7: [ Maarten Lankhorst ] Set cb->func and only enable sw signaling if
    fence wasn't signaled yet, for example for hardware fences that may
    choose to signal blindly.
v8: [ Maarten Lankhorst ] Tons of tiny fixes, moved __dma_fence_init to
    header and fixed include mess. dma-fence.h now includes dma-buf.h
    All members are now initialized, so kmalloc can be used for
    allocating a dma-fence. More documentation added.
v9: Change compiler bitfields to flags, change return type of
    enable_signaling to bool. Rework dma_fence_wait. Added
    dma_fence_is_signaled and dma_fence_wait_timeout.
    s/dma// and change exports to non GPL. Added fence_is_signaled and
    fence_enable_sw_signaling calls, add ability to override default
    wait operation.
v10: remove event_queue, use a custom list, export try_to_wake_up from
    scheduler. Remove fence lock and use a global spinlock instead,
    this should hopefully remove all the locking headaches I was having
    on trying to implement this. enable_signaling is called with this
    lock held.
v11:
    Use atomic ops for flags, lifting the need for some spin_lock_irqsaves.
    However I kept the guarantee that after fence_signal returns, it is
    guaranteed that enable_signaling has either been called to completion,
    or will not be called any more.

    Add contexts and seqno to base fence implementation. This allows you
    to wait for less fences, by testing for seqno + signaled, and then only
    wait on the later fence.

    Add FENCE_TRACE, FENCE_WARN, and FENCE_ERR. This makes debugging easier.
    An CONFIG_DEBUG_FENCE will be added to turn off the FENCE_TRACE
    spam, and another runtime option can turn it off at runtime.
v12:
    Add CONFIG_FENCE_TRACE. Add missing documentation for the fence->context
    and fence->seqno members.
v13:
    Fixup CONFIG_FENCE_TRACE kconfig description.
    Move fence_context_alloc to fence.
    Simplify fence_later.
    Kill priv member to fence_cb.
v14:
    Remove priv argument from fence_add_callback, oops!
v15:
    Remove priv from documentation.
    Explicitly include linux/atomic.h.
v16:
    Add trace events.
    Import changes required by android syncpoints.
v17:
    Use wake_up_state instead of try_to_wake_up. (Colin Cross)
    Fix up commit description for seqno_fence. (Rob Clark)
v18:
    Rename release_fence to fence_release.
    Move to drivers/dma-buf/.
    Rename __fence_is_signaled and __fence_signal to *_locked.
    Rename __fence_init to fence_init.
    Make fence_default_wait return a signed long, and fix wait ops too.
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com> #use smp_mb__before_atomic()
Acked-by: NSumit Semwal <sumit.semwal@linaro.org>
Acked-by: NDaniel Vetter <daniel@ffwll.ch>
Reviewed-by: NRob Clark <robdclark@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      e941759c
  43. 24 6月, 2014 1 次提交
  45. 22 6月, 2014 1 次提交
  47. 21 6月, 2014 1 次提交
    • S
      tracing: Add __field_struct macro for TRACE_EVENT() · 4d4c9cc8
      由 Steven Rostedt 提交于 
      Currently the __field() macro in TRACE_EVENT is only good for primitive
values, such as integers and pointers, but it fails on complex data types
such as structures or unions. This is because the __field() macro
determines if the variable is signed or not with the test of:

  (((type)(-1)) < (type)1)

Unfortunately, that fails when type is a structure.

Since trace events should support structures as fields a new macro
is created for such a case called __field_struct() which acts exactly
the same as __field() does but it does not do the signed type check
and just uses a constant false for that answer.

Cc: Tony Luck <tony.luck@gmail.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      4d4c9cc8