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  1. 23 6月, 2013 3 次提交
    • D
      x86: Add NMI duration tracepoints · 0c4df02d
      由 Dave Hansen 提交于 
      This patch has been invaluable in my adventures finding
issues in the perf NMI handler.  I'm as big a fan of
printk() as anybody is, but using printk() in NMIs is
deadly when they're happening frequently.

Even hacking in trace_printk() ended up eating enough
CPU to throw off some of the measurements I was making.
Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus@samba.org
Cc: acme@ghostprotocols.net
Cc: Dave Hansen <dave@sr71.net>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      0c4df02d
    • D
      perf: Drop sample rate when sampling is too slow · 14c63f17
      由 Dave Hansen 提交于 
      This patch keeps track of how long perf's NMI handler is taking,
and also calculates how many samples perf can take a second.  If
the sample length times the expected max number of samples
exceeds a configurable threshold, it drops the sample rate.

This way, we don't have a runaway sampling process eating up the
CPU.

This patch can tend to drop the sample rate down to level where
perf doesn't work very well.  *BUT* the alternative is that my
system hangs because it spends all of its time handling NMIs.

I'll take a busted performance tool over an entire system that's
busted and undebuggable any day.

BTW, my suspicion is that there's still an underlying bug here.
Using the HPET instead of the TSC is definitely a contributing
factor, but I suspect there are some other things going on.
But, I can't go dig down on a bug like that with my machine
hanging all the time.
Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus@samba.org
Cc: acme@ghostprotocols.net
Cc: Dave Hansen <dave@sr71.net>
[ Prettified it a bit. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      14c63f17
    • D
      x86: Warn when NMI handlers take large amounts of time · 2ab00456
      由 Dave Hansen 提交于 
      I have a system which is causing all kinds of problems.  It has
8 NUMA nodes, and lots of cores that can fight over cachelines.
If things are not working _perfectly_, then NMIs can take longer
than expected.

If we get too many of them backed up to each other, we can
easily end up in a situation where we are doing nothing *but*
running NMIs.  The biggest problem, though, is that this happens
_silently_.  You might be lucky to get an hrtimer warning, but
most of the time system simply hangs.

This patch should at least give us some warning before we fall
off the cliff.  the warnings look like this:

	nmi_handle: perf_event_nmi_handler() took: 26095071 ns

The message is triggered whenever we notice the longest NMI
we've seen to date.  You can always view and reset this value
via the debugfs interface if you like.
Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus@samba.org
Cc: acme@ghostprotocols.net
Cc: Dave Hansen <dave@sr71.net>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      2ab00456
  3. 20 6月, 2013 1 次提交
  5. 19 6月, 2013 12 次提交
  7. 29 5月, 2013 1 次提交
  9. 28 5月, 2013 6 次提交
  11. 26 5月, 2013 1 次提交
  13. 25 5月, 2013 6 次提交
    • V
      ARC: lazy dcache flush broke gdb in non-aliasing configs · 7bb66f6e
      由 Vineet Gupta 提交于 
      gdbserver inserting a breakpoint ends up calling copy_user_page() for a
code page. The generic version of which (non-aliasing config) didn't set
the PG_arch_1 bit hence update_mmu_cache() didn't sync dcache/icache for
corresponding dynamic loader code page - causing garbade to be executed.

So now aliasing versions of copy_user_highpage()/clear_page() are made
default. There is no significant overhead since all of special alias
handling code is compiled out for non-aliasing build
Signed-off-by: NVineet Gupta <vgupta@synopsys.com>
      7bb66f6e
    • H
      parisc: fix irq stack on UP and SMP · d96b51ec
      由 Helge Deller 提交于 
      The logic to detect if the irq stack was already in use with
raw_spin_trylock() is wrong, because it will generate a "trylock failure
on UP" error message with CONFIG_SMP=n and CONFIG_DEBUG_SPINLOCK=y.

arch_spin_trylock() can't be used either since in the CONFIG_SMP=n case
no atomic protection is given and we are reentrant here. A mutex didn't
worked either and brings more overhead by turning off interrupts.

So, let's use the fastest path for parisc which is the ldcw instruction.

Counting how often the irq stack was used is pretty useless, so just
drop this piece of code.
Signed-off-by: NHelge Deller <deller@gmx.de>
      d96b51ec
    • J
      parisc: make interrupt and interruption stack allocation reentrant · b63a2bbc
      由 John David Anglin 提交于 
      The get_stack_use_cr30 and get_stack_use_r30 macros allocate a stack
frame for external interrupts and interruptions requiring a stack frame.
They are currently not reentrant in that they save register context
before the stack is set or adjusted.

I have observed a number of system crashes where there was clear
evidence of stack corruption during interrupt processing, and as a
result register corruption. Some interruptions can still occur during
interruption processing, however external interrupts are disabled and
data TLB misses don't occur for absolute accesses. So, it's not entirely
clear what triggers this issue. Also, if an interruption occurs when
Q=0, it is generally not possible to recover as the shadowed registers
are not copied.

The attached patch reworks the get_stack_use_cr30 and get_stack_use_r30
macros to allocate stack before doing register saves. The new code is a
couple of instructions shorter than the old implementation. Thus, it's
an improvement even if it doesn't fully resolve the stack corruption
issue. Based on limited testing, it improves SMP system stability.
Signed-off-by: NJohn David Anglin <dave.anglin@bell.net>
Signed-off-by: NHelge Deller <deller@gmx.de>
      b63a2bbc
    • H
      parisc: show number of FPE and unaligned access handler calls in /proc/interrupts · d0c3be80
      由 Helge Deller 提交于 
      Show number of floating point assistant and unaligned access fixup
handler in /proc/interrupts file.
Signed-off-by: NHelge Deller <deller@gmx.de>
      d0c3be80
    • H
      parisc: use PAGE_SHIFT instead of hardcoded value 12 in pacache.S · d845b5fb
      由 Helge Deller 提交于 
      additionally clean up some whitespaces & tabs.
Signed-off-by: NHelge Deller <deller@gmx.de>
      d845b5fb
    • H
      parisc: add rp5470 entry to machine database · 949451b9
      由 Helge Deller 提交于 
      Signed-off-by: NHelge Deller <deller@gmx.de>
      949451b9
  15. 24 5月, 2013 10 次提交