<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/tools/perf/util/trace-event-parse.c, branch v3.2.9</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>perf: Fix parsing of __print_flags() in TP_printk()</title>
<updated>2012-01-12T19:29:27+00:00</updated>
<author>
<name>Steven Rostedt</name>
<email>srostedt@redhat.com</email>
</author>
<published>2011-11-04T20:32:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=923415295307845e614589c1cce62abedd4d1731'/>
<id>923415295307845e614589c1cce62abedd4d1731</id>
<content type='text'>
commit 49908a1b25d448d68fd26faca260e1850201575f upstream.

A update is made to the sched:sched_switch event that adds some
logic to the first parameter of the __print_flags() that shows the
state of tasks. This change cause perf to fail parsing the flags.

A simple fix is needed to have the parser be able to process ops
within the argument.

Reported-by: Andrew Vagin &lt;avagin@openvz.org&gt;
Signed-off-by: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 49908a1b25d448d68fd26faca260e1850201575f upstream.

A update is made to the sched:sched_switch event that adds some
logic to the first parameter of the __print_flags() that shows the
state of tasks. This change cause perf to fail parsing the flags.

A simple fix is needed to have the parser be able to process ops
within the argument.

Reported-by: Andrew Vagin &lt;avagin@openvz.org&gt;
Signed-off-by: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@suse.de&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>perf: Fix parsing of __print_flags() in TP_printk()</title>
<updated>2011-12-05T18:28:47+00:00</updated>
<author>
<name>Steven Rostedt</name>
<email>srostedt@redhat.com</email>
</author>
<published>2011-11-04T20:32:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=d06c27b22aa66e48e32f03f9387328a9af9b0625'/>
<id>d06c27b22aa66e48e32f03f9387328a9af9b0625</id>
<content type='text'>
A update is made to the sched:sched_switch event that adds some
logic to the first parameter of the __print_flags() that shows the
state of tasks. This change cause perf to fail parsing the flags.

A simple fix is needed to have the parser be able to process ops
within the argument.

Cc: stable@vger.kernel.org
Reported-by: Andrew Vagin &lt;avagin@openvz.org&gt;
Signed-off-by: Steven Rostedt &lt;rostedt@goodmis.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
A update is made to the sched:sched_switch event that adds some
logic to the first parameter of the __print_flags() that shows the
state of tasks. This change cause perf to fail parsing the flags.

A simple fix is needed to have the parser be able to process ops
within the argument.

Cc: stable@vger.kernel.org
Reported-by: Andrew Vagin &lt;avagin@openvz.org&gt;
Signed-off-by: Steven Rostedt &lt;rostedt@goodmis.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu: Use softirq to address performance regression</title>
<updated>2011-06-14T22:25:39+00:00</updated>
<author>
<name>Shaohua Li</name>
<email>shaohua.li@intel.com</email>
</author>
<published>2011-06-14T05:26:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=09223371deac67d08ca0b70bd18787920284c967'/>
<id>09223371deac67d08ca0b70bd18787920284c967</id>
<content type='text'>
Commit a26ac2455ffcf3(rcu: move TREE_RCU from softirq to kthread)
introduced performance regression. In an AIM7 test, this commit degraded
performance by about 40%.

The commit runs rcu callbacks in a kthread instead of softirq. We observed
high rate of context switch which is caused by this. Out test system has
64 CPUs and HZ is 1000, so we saw more than 64k context switch per second
which is caused by RCU's per-CPU kthread.  A trace showed that most of
the time the RCU per-CPU kthread doesn't actually handle any callbacks,
but instead just does a very small amount of work handling grace periods.
This means that RCU's per-CPU kthreads are making the scheduler do quite
a bit of work in order to allow a very small amount of RCU-related
processing to be done.

Alex Shi's analysis determined that this slowdown is due to lock
contention within the scheduler.  Unfortunately, as Peter Zijlstra points
out, the scheduler's real-time semantics require global action, which
means that this contention is inherent in real-time scheduling.  (Yes,
perhaps someone will come up with a workaround -- otherwise, -rt is not
going to do well on large SMP systems -- but this patch will work around
this issue in the meantime.  And "the meantime" might well be forever.)

This patch therefore re-introduces softirq processing to RCU, but only
for core RCU work.  RCU callbacks are still executed in kthread context,
so that only a small amount of RCU work runs in softirq context in the
common case.  This should minimize ksoftirqd execution, allowing us to
skip boosting of ksoftirqd for CONFIG_RCU_BOOST=y kernels.

Signed-off-by: Shaohua Li &lt;shaohua.li@intel.com&gt;
Tested-by: "Alex,Shi" &lt;alex.shi@intel.com&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@linux.vnet.ibm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Commit a26ac2455ffcf3(rcu: move TREE_RCU from softirq to kthread)
introduced performance regression. In an AIM7 test, this commit degraded
performance by about 40%.

The commit runs rcu callbacks in a kthread instead of softirq. We observed
high rate of context switch which is caused by this. Out test system has
64 CPUs and HZ is 1000, so we saw more than 64k context switch per second
which is caused by RCU's per-CPU kthread.  A trace showed that most of
the time the RCU per-CPU kthread doesn't actually handle any callbacks,
but instead just does a very small amount of work handling grace periods.
This means that RCU's per-CPU kthreads are making the scheduler do quite
a bit of work in order to allow a very small amount of RCU-related
processing to be done.

Alex Shi's analysis determined that this slowdown is due to lock
contention within the scheduler.  Unfortunately, as Peter Zijlstra points
out, the scheduler's real-time semantics require global action, which
means that this contention is inherent in real-time scheduling.  (Yes,
perhaps someone will come up with a workaround -- otherwise, -rt is not
going to do well on large SMP systems -- but this patch will work around
this issue in the meantime.  And "the meantime" might well be forever.)

This patch therefore re-introduces softirq processing to RCU, but only
for core RCU work.  RCU callbacks are still executed in kthread context,
so that only a small amount of RCU work runs in softirq context in the
common case.  This should minimize ksoftirqd execution, allowing us to
skip boosting of ksoftirqd for CONFIG_RCU_BOOST=y kernels.

Signed-off-by: Shaohua Li &lt;shaohua.li@intel.com&gt;
Tested-by: "Alex,Shi" &lt;alex.shi@intel.com&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@linux.vnet.ibm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>rcu: move TREE_RCU from softirq to kthread</title>
<updated>2011-05-06T06:16:54+00:00</updated>
<author>
<name>Paul E. McKenney</name>
<email>paul.mckenney@linaro.org</email>
</author>
<published>2011-01-12T22:10:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a26ac2455ffcf3be5c6ef92bc6df7182700f2114'/>
<id>a26ac2455ffcf3be5c6ef92bc6df7182700f2114</id>
<content type='text'>
If RCU priority boosting is to be meaningful, callback invocation must
be boosted in addition to preempted RCU readers.  Otherwise, in presence
of CPU real-time threads, the grace period ends, but the callbacks don't
get invoked.  If the callbacks don't get invoked, the associated memory
doesn't get freed, so the system is still subject to OOM.

But it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit
moves the callback invocations to a kthread, which can be boosted easily.

Also add comments and properly synchronized all accesses to
rcu_cpu_kthread_task, as suggested by Lai Jiangshan.

Signed-off-by: Paul E. McKenney &lt;paul.mckenney@linaro.org&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@linux.vnet.ibm.com&gt;
Reviewed-by: Josh Triplett &lt;josh@joshtriplett.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
If RCU priority boosting is to be meaningful, callback invocation must
be boosted in addition to preempted RCU readers.  Otherwise, in presence
of CPU real-time threads, the grace period ends, but the callbacks don't
get invoked.  If the callbacks don't get invoked, the associated memory
doesn't get freed, so the system is still subject to OOM.

But it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit
moves the callback invocations to a kthread, which can be boosted easily.

Also add comments and properly synchronized all accesses to
rcu_cpu_kthread_task, as suggested by Lai Jiangshan.

Signed-off-by: Paul E. McKenney &lt;paul.mckenney@linaro.org&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@linux.vnet.ibm.com&gt;
Reviewed-by: Josh Triplett &lt;josh@joshtriplett.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf script: Move printing of 'common' data from print_event and rename</title>
<updated>2011-03-14T20:05:55+00:00</updated>
<author>
<name>David Ahern</name>
<email>daahern@cisco.com</email>
</author>
<published>2011-03-10T05:23:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=c70c94b47405d2c94df19c16273daf1f5fb9193d'/>
<id>c70c94b47405d2c94df19c16273daf1f5fb9193d</id>
<content type='text'>
This change does impact output: latency data is trace specific and is
now printed after the common data - comm, tid, cpu, time and event name.

Acked-by: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
LKML-Reference: &lt;1299734608-5223-4-git-send-email-daahern@cisco.com&gt;
Signed-off-by: David Ahern &lt;daahern@cisco.com&gt;
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This change does impact output: latency data is trace specific and is
now printed after the common data - comm, tid, cpu, time and event name.

Acked-by: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
LKML-Reference: &lt;1299734608-5223-4-git-send-email-daahern@cisco.com&gt;
Signed-off-by: David Ahern &lt;daahern@cisco.com&gt;
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf tracing: Remove print_graph_cpu and print_graph_proc from trace-event-parse</title>
<updated>2011-03-14T20:05:51+00:00</updated>
<author>
<name>David Ahern</name>
<email>daahern@cisco.com</email>
</author>
<published>2011-03-10T05:23:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=2ee7a49f935b19f7daf0a110800488acd2479cba'/>
<id>2ee7a49f935b19f7daf0a110800488acd2479cba</id>
<content type='text'>
Next patch moves printing of 'common' data into perf-script which
removes the need for these functions.

Acked-by: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
LKML-Reference: &lt;1299734608-5223-3-git-send-email-daahern@cisco.com&gt;
Signed-off-by: David Ahern &lt;daahern@cisco.com&gt;
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Next patch moves printing of 'common' data into perf-script which
removes the need for these functions.

Acked-by: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
LKML-Reference: &lt;1299734608-5223-3-git-send-email-daahern@cisco.com&gt;
Signed-off-by: David Ahern &lt;daahern@cisco.com&gt;
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf tool: Fix gcc 4.6.0 issues</title>
<updated>2011-02-07T14:41:41+00:00</updated>
<author>
<name>Kyle McMartin</name>
<email>kyle@mcmartin.ca</email>
</author>
<published>2011-01-24T16:13:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=fb7d0b3cefb80a105f7fd26bbc62e0cbf9192822'/>
<id>fb7d0b3cefb80a105f7fd26bbc62e0cbf9192822</id>
<content type='text'>
GCC 4.6.0 in Fedora rawhide turned up some compile errors in tools/perf
due to the -Werror=unused-but-set-variable flag.

I've gone through and annotated some of the assignments that had side
effects (ie: return value from a function) with the __used annotation,
and in some cases, just removed unused code.

In a few cases, we were assigning something useful, but not using it in
later parts of the function.

kyle@dreadnought:~/src% gcc --version
gcc (GCC) 4.6.0 20110122 (Red Hat 4.6.0-0.3)

Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
LKML-Reference: &lt;20110124161304.GK27353@bombadil.infradead.org&gt;
Signed-off-by: Kyle McMartin &lt;kyle@redhat.com&gt;
[ committer note: Fixed up the annotation fixes, as that code moved recently ]
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
GCC 4.6.0 in Fedora rawhide turned up some compile errors in tools/perf
due to the -Werror=unused-but-set-variable flag.

I've gone through and annotated some of the assignments that had side
effects (ie: return value from a function) with the __used annotation,
and in some cases, just removed unused code.

In a few cases, we were assigning something useful, but not using it in
later parts of the function.

kyle@dreadnought:~/src% gcc --version
gcc (GCC) 4.6.0 20110122 (Red Hat 4.6.0-0.3)

Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
LKML-Reference: &lt;20110124161304.GK27353@bombadil.infradead.org&gt;
Signed-off-by: Kyle McMartin &lt;kyle@redhat.com&gt;
[ committer note: Fixed up the annotation fixes, as that code moved recently ]
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip</title>
<updated>2010-05-18T15:19:03+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2010-05-18T15:19:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=4d7b4ac22fbec1a03206c6cde353f2fd6942f828'/>
<id>4d7b4ac22fbec1a03206c6cde353f2fd6942f828</id>
<content type='text'>
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (311 commits)
  perf tools: Add mode to build without newt support
  perf symbols: symbol inconsistency message should be done only at verbose=1
  perf tui: Add explicit -lslang option
  perf options: Type check all the remaining OPT_ variants
  perf options: Type check OPT_BOOLEAN and fix the offenders
  perf options: Check v type in OPT_U?INTEGER
  perf options: Introduce OPT_UINTEGER
  perf tui: Add workaround for slang &lt; 2.1.4
  perf record: Fix bug mismatch with -c option definition
  perf options: Introduce OPT_U64
  perf tui: Add help window to show key associations
  perf tui: Make &lt;- exit menus too
  perf newt: Add single key shortcuts for zoom into DSO and threads
  perf newt: Exit browser unconditionally when CTRL+C, q or Q is pressed
  perf newt: Fix the 'A'/'a' shortcut for annotate
  perf newt: Make &lt;- exit the ui_browser
  x86, perf: P4 PMU - fix counters management logic
  perf newt: Make &lt;- zoom out filters
  perf report: Report number of events, not samples
  perf hist: Clarify events_stats fields usage
  ...

Fix up trivial conflicts in kernel/fork.c and tools/perf/builtin-record.c
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (311 commits)
  perf tools: Add mode to build without newt support
  perf symbols: symbol inconsistency message should be done only at verbose=1
  perf tui: Add explicit -lslang option
  perf options: Type check all the remaining OPT_ variants
  perf options: Type check OPT_BOOLEAN and fix the offenders
  perf options: Check v type in OPT_U?INTEGER
  perf options: Introduce OPT_UINTEGER
  perf tui: Add workaround for slang &lt; 2.1.4
  perf record: Fix bug mismatch with -c option definition
  perf options: Introduce OPT_U64
  perf tui: Add help window to show key associations
  perf tui: Make &lt;- exit menus too
  perf newt: Add single key shortcuts for zoom into DSO and threads
  perf newt: Exit browser unconditionally when CTRL+C, q or Q is pressed
  perf newt: Fix the 'A'/'a' shortcut for annotate
  perf newt: Make &lt;- exit the ui_browser
  x86, perf: P4 PMU - fix counters management logic
  perf newt: Make &lt;- zoom out filters
  perf report: Report number of events, not samples
  perf hist: Clarify events_stats fields usage
  ...

Fix up trivial conflicts in kernel/fork.c and tools/perf/builtin-record.c
</pre>
</div>
</content>
</entry>
<entry>
<title>perf: Fix static strings treated like dynamic ones</title>
<updated>2010-05-11T07:14:24+00:00</updated>
<author>
<name>Frederic Weisbecker</name>
<email>fweisbec@gmail.com</email>
</author>
<published>2010-05-05T20:07:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=de068ec048f807d4f62b7dda100c23a1365f086f'/>
<id>de068ec048f807d4f62b7dda100c23a1365f086f</id>
<content type='text'>
The raw_field_ptr() helper, used to retrieve the address of a field
inside a trace event, treats every strings as if they were dynamic
ie: having a secondary level of indirection to retrieve their
contents.

FIELD_IS_STRING doesn't mean FIELD_IS_DYNAMIC, we only need to
compute the secondary dereference for the latter case.

This fixes perf sched segfaults, bad cmdline report and may be
some other bugs.

Reported-by: Jason Baron &lt;jbaron@redhat.com&gt;
Reported-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Tom Zanussi &lt;tzanussi@gmail.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The raw_field_ptr() helper, used to retrieve the address of a field
inside a trace event, treats every strings as if they were dynamic
ie: having a secondary level of indirection to retrieve their
contents.

FIELD_IS_STRING doesn't mean FIELD_IS_DYNAMIC, we only need to
compute the secondary dereference for the latter case.

This fixes perf sched segfaults, bad cmdline report and may be
some other bugs.

Reported-by: Jason Baron &lt;jbaron@redhat.com&gt;
Reported-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Tom Zanussi &lt;tzanussi@gmail.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>perf: Fix warning while reading ring buffer headers</title>
<updated>2010-05-01T02:31:48+00:00</updated>
<author>
<name>Frederic Weisbecker</name>
<email>fweisbec@gmail.com</email>
</author>
<published>2010-05-01T01:08:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=d00a47cce569a3e660a8c9de5d57af28d6a9f0f7'/>
<id>d00a47cce569a3e660a8c9de5d57af28d6a9f0f7</id>
<content type='text'>
commit e9e94e3bd862d31777335722e747e97d9821bc1d
"perf trace: Ignore "overwrite" field if present in
/events/header_page" makes perf trace launching spurious warnings
about unexpected tokens read:

	Warning: Error: expected type 6 but read 4

This change tries to handle the overcommit field in the header_page
file whenever this field is present or not.

The problem is that if this field is not present, we try to find it
and give up in the middle of the line when we realize we are actually
dealing with another field, which is the "data" one. And this failure
abandons the file pointer in the middle of the "data" description
line:

	field: u64 timestamp;	offset:0;	size:8;	signed:0;
	field: local_t commit;	offset:8;	size:8;	signed:1;
	field: char data;	offset:16;	size:4080;	signed:1;
                      ^^^
                      Here

What happens next is that we want to read this line to parse the data
field, but we fail because the pointer is not in the beginning of the
line.

We could probably fix that by rewinding the pointer. But in fact we
don't care much about these headers that only concern the ftrace
ring-buffer. We don't use them from perf.

Just skip this part of perf.data, but don't remove it from recording
to stay compatible with olders perf.data

Signed-off-by: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit e9e94e3bd862d31777335722e747e97d9821bc1d
"perf trace: Ignore "overwrite" field if present in
/events/header_page" makes perf trace launching spurious warnings
about unexpected tokens read:

	Warning: Error: expected type 6 but read 4

This change tries to handle the overcommit field in the header_page
file whenever this field is present or not.

The problem is that if this field is not present, we try to find it
and give up in the middle of the line when we realize we are actually
dealing with another field, which is the "data" one. And this failure
abandons the file pointer in the middle of the "data" description
line:

	field: u64 timestamp;	offset:0;	size:8;	signed:0;
	field: local_t commit;	offset:8;	size:8;	signed:1;
	field: char data;	offset:16;	size:4080;	signed:1;
                      ^^^
                      Here

What happens next is that we want to read this line to parse the data
field, but we fail because the pointer is not in the beginning of the
line.

We could probably fix that by rewinding the pointer. But in fact we
don't care much about these headers that only concern the ftrace
ring-buffer. We don't use them from perf.

Just skip this part of perf.data, but don't remove it from recording
to stay compatible with olders perf.data

Signed-off-by: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Stephane Eranian &lt;eranian@google.com&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
</pre>
</div>
</content>
</entry>
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