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  1. 27 Apr, 2010 2 commits
    • David Miller's avatar
      ring-buffer: Make non-consuming read less expensive with lots of cpus. · 72c9ddfd
      David Miller authored 
      When performing a non-consuming read, a synchronize_sched() is
performed once for every cpu which is actively tracing.

This is very expensive, and can make it take several seconds to open
up the 'trace' file with lots of cpus.

Only one synchronize_sched() call is actually necessary.  What is
desired is for all cpus to see the disabling state change.  So we
transform the existing sequence:

	for_each_cpu() {
		ring_buffer_read_start();
	}

where each ring_buffer_start() call performs a synchronize_sched(),
into the following:

	for_each_cpu() {
		ring_buffer_read_prepare();
	}
	ring_buffer_read_prepare_sync();
	for_each_cpu() {
		ring_buffer_read_start();
	}

wherein only the single ring_buffer_read_prepare_sync() call needs to
do the synchronize_sched().

The first phase, via ring_buffer_read_prepare(), allocates the 'iter'
memory and increments ->record_disabled.

In the second phase, ring_buffer_read_prepare_sync() makes sure this
->record_disabled state is visible fully to all cpus.

And in the final third phase, the ring_buffer_read_start() calls reset
the 'iter' objects allocated in the first phase since we now know that
none of the cpus are adding trace entries any more.

This makes openning the 'trace' file nearly instantaneous on a
sparc64 Niagara2 box with 128 cpus tracing.
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
LKML-Reference: <20100420.154711.11246950.davem@davemloft.net>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      72c9ddfd
    • Jiri Olsa's avatar
      tracing: Add graph output support for irqsoff tracer · 62b915f1
      Jiri Olsa authored 
      Add function graph output to irqsoff tracer.

The graph output is enabled by setting new 'display-graph' trace option.
Signed-off-by: default avatarJiri Olsa <jolsa@redhat.com>
LKML-Reference: <1270227683-14631-4-git-send-email-jolsa@redhat.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      62b915f1
  3. 26 Apr, 2010 2 commits
  5. 23 Apr, 2010 1 commit
  7. 21 Apr, 2010 2 commits
    • Frederic Weisbecker's avatar
      tracing: Dump either the oops's cpu source or all cpus buffers · cecbca96
      Frederic Weisbecker authored 
      The ftrace_dump_on_oops kernel parameter, sysctl and sysrq let one
dump every cpu buffers when an oops or panic happens.

It's nice when you have few cpus but it may take ages if have many,
plus you miss the real origin of the problem in all the cpu traces.

Sometimes, all you need is to dump the cpu buffer that triggered the
opps, most of the time it is our main interest.

This patch modifies ftrace_dump_on_oops to handle this choice.

The ftrace_dump_on_oops kernel parameter, when it comes alone, has
the same behaviour than before. But ftrace_dump_on_oops=orig_cpu
will only dump the buffer of the cpu that oops'ed.

Similarly, sysctl kernel.ftrace_dump_on_oops=1 and
echo 1 > /proc/sys/kernel/ftrace_dump_on_oops keep their previous
behaviour. But setting 2 jumps into cpu origin dump mode.

v2: Fix double setup
v3: Fix spelling issues reported by Randy Dunlap
v4: Also update __ftrace_dump in the selftests
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
      cecbca96
    • Ingo Molnar's avatar
      Merge commit 'v2.6.34-rc5' into tracing/core · ac0053fd
      Ingo Molnar authored 
      Merge reason: pick up latest -rc's.
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      ac0053fd
  9. 19 Apr, 2010 24 commits
  11. 18 Apr, 2010 1 commit
  13. 17 Apr, 2010 3 commits
  15. 16 Apr, 2010 5 commits
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