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Merge branches 'sched/core', 'core/core' and 'tracing/core' into cpus…
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Ingo Molnar committed Nov 24, 2008
3 parents 64b7482 + b19b3c7 + 6f893fb commit 943f3d0
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62 changes: 32 additions & 30 deletions Documentation/ftrace.txt
Original file line number Diff line number Diff line change
Expand Up @@ -82,7 +82,7 @@ of ftrace. Here is a list of some of the key files:
tracer is not adding more data, they will display
the same information every time they are read.

iter_ctrl: This file lets the user control the amount of data
trace_options: This file lets the user control the amount of data
that is displayed in one of the above output
files.

Expand All @@ -94,10 +94,10 @@ of ftrace. Here is a list of some of the key files:
only be recorded if the latency is greater than
the value in this file. (in microseconds)

trace_entries: This sets or displays the number of bytes each CPU
buffer_size_kb: This sets or displays the number of kilobytes each CPU
buffer can hold. The tracer buffers are the same size
for each CPU. The displayed number is the size of the
CPU buffer and not total size of all buffers. The
CPU buffer and not total size of all buffers. The
trace buffers are allocated in pages (blocks of memory
that the kernel uses for allocation, usually 4 KB in size).
If the last page allocated has room for more bytes
Expand Down Expand Up @@ -316,23 +316,23 @@ The above is mostly meaningful for kernel developers.
The rest is the same as the 'trace' file.


iter_ctrl
---------
trace_options
-------------

The iter_ctrl file is used to control what gets printed in the trace
The trace_options file is used to control what gets printed in the trace
output. To see what is available, simply cat the file:

cat /debug/tracing/iter_ctrl
cat /debug/tracing/trace_options
print-parent nosym-offset nosym-addr noverbose noraw nohex nobin \
noblock nostacktrace nosched-tree
noblock nostacktrace nosched-tree nouserstacktrace nosym-userobj

To disable one of the options, echo in the option prepended with "no".

echo noprint-parent > /debug/tracing/iter_ctrl
echo noprint-parent > /debug/tracing/trace_options

To enable an option, leave off the "no".

echo sym-offset > /debug/tracing/iter_ctrl
echo sym-offset > /debug/tracing/trace_options

Here are the available options:

Expand Down Expand Up @@ -378,6 +378,20 @@ Here are the available options:
When a trace is recorded, so is the stack of functions.
This allows for back traces of trace sites.

userstacktrace - This option changes the trace.
It records a stacktrace of the current userspace thread.

sym-userobj - when user stacktrace are enabled, look up which object the
address belongs to, and print a relative address
This is especially useful when ASLR is on, otherwise you don't
get a chance to resolve the address to object/file/line after the app is no
longer running

The lookup is performed when you read trace,trace_pipe,latency_trace. Example:

a.out-1623 [000] 40874.465068: /root/a.out[+0x480] <-/root/a.out[+0
x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]

sched-tree - TBD (any users??)


Expand Down Expand Up @@ -1299,41 +1313,29 @@ trace entries
-------------

Having too much or not enough data can be troublesome in diagnosing
an issue in the kernel. The file trace_entries is used to modify
an issue in the kernel. The file buffer_size_kb is used to modify
the size of the internal trace buffers. The number listed
is the number of entries that can be recorded per CPU. To know
the full size, multiply the number of possible CPUS with the
number of entries.

# cat /debug/tracing/trace_entries
65620
# cat /debug/tracing/buffer_size_kb
1408 (units kilobytes)

Note, to modify this, you must have tracing completely disabled. To do that,
echo "nop" into the current_tracer. If the current_tracer is not set
to "nop", an EINVAL error will be returned.

# echo nop > /debug/tracing/current_tracer
# echo 100000 > /debug/tracing/trace_entries
# cat /debug/tracing/trace_entries
100045


Notice that we echoed in 100,000 but the size is 100,045. The entries
are held in individual pages. It allocates the number of pages it takes
to fulfill the request. If more entries may fit on the last page
then they will be added.

# echo 1 > /debug/tracing/trace_entries
# cat /debug/tracing/trace_entries
85

This shows us that 85 entries can fit in a single page.
# echo 10000 > /debug/tracing/buffer_size_kb
# cat /debug/tracing/buffer_size_kb
10000 (units kilobytes)

The number of pages which will be allocated is limited to a percentage
of available memory. Allocating too much will produce an error.

# echo 1000000000000 > /debug/tracing/trace_entries
# echo 1000000000000 > /debug/tracing/buffer_size_kb
-bash: echo: write error: Cannot allocate memory
# cat /debug/tracing/trace_entries
# cat /debug/tracing/buffer_size_kb
85

8 changes: 8 additions & 0 deletions Documentation/kernel-parameters.txt
Original file line number Diff line number Diff line change
Expand Up @@ -750,6 +750,14 @@ and is between 256 and 4096 characters. It is defined in the file
parameter will force ia64_sal_cache_flush to call
ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.

ftrace=[tracer]
[ftrace] will set and start the specified tracer
as early as possible in order to facilitate early
boot debugging.

ftrace_dump_on_oops
[ftrace] will dump the trace buffers on oops.

gamecon.map[2|3]=
[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
support via parallel port (up to 5 devices per port)
Expand Down
51 changes: 33 additions & 18 deletions Documentation/lockstat.txt
Original file line number Diff line number Diff line change
Expand Up @@ -71,35 +71,50 @@ Look at the current lock statistics:

# less /proc/lock_stat

01 lock_stat version 0.2
01 lock_stat version 0.3
02 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
03 class name con-bounces contentions waittime-min waittime-max waittime-total acq-bounces acquisitions holdtime-min holdtime-max holdtime-total
04 -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
05
06 &inode->i_data.tree_lock-W: 15 21657 0.18 1093295.30 11547131054.85 58 10415 0.16 87.51 6387.60
07 &inode->i_data.tree_lock-R: 0 0 0.00 0.00 0.00 23302 231198 0.25 8.45 98023.38
08 --------------------------
09 &inode->i_data.tree_lock 0 [<ffffffff8027c08f>] add_to_page_cache+0x5f/0x190
10
11 ...............................................................................................................................................................................................
12
13 dcache_lock: 1037 1161 0.38 45.32 774.51 6611 243371 0.15 306.48 77387.24
14 -----------
15 dcache_lock 180 [<ffffffff802c0d7e>] sys_getcwd+0x11e/0x230
16 dcache_lock 165 [<ffffffff802c002a>] d_alloc+0x15a/0x210
17 dcache_lock 33 [<ffffffff8035818d>] _atomic_dec_and_lock+0x4d/0x70
18 dcache_lock 1 [<ffffffff802beef8>] shrink_dcache_parent+0x18/0x130
06 &mm->mmap_sem-W: 233 538 18446744073708 22924.27 607243.51 1342 45806 1.71 8595.89 1180582.34
07 &mm->mmap_sem-R: 205 587 18446744073708 28403.36 731975.00 1940 412426 0.58 187825.45 6307502.88
08 ---------------
09 &mm->mmap_sem 487 [<ffffffff8053491f>] do_page_fault+0x466/0x928
10 &mm->mmap_sem 179 [<ffffffff802a6200>] sys_mprotect+0xcd/0x21d
11 &mm->mmap_sem 279 [<ffffffff80210a57>] sys_mmap+0x75/0xce
12 &mm->mmap_sem 76 [<ffffffff802a490b>] sys_munmap+0x32/0x59
13 ---------------
14 &mm->mmap_sem 270 [<ffffffff80210a57>] sys_mmap+0x75/0xce
15 &mm->mmap_sem 431 [<ffffffff8053491f>] do_page_fault+0x466/0x928
16 &mm->mmap_sem 138 [<ffffffff802a490b>] sys_munmap+0x32/0x59
17 &mm->mmap_sem 145 [<ffffffff802a6200>] sys_mprotect+0xcd/0x21d
18
19 ...............................................................................................................................................................................................
20
21 dcache_lock: 621 623 0.52 118.26 1053.02 6745 91930 0.29 316.29 118423.41
22 -----------
23 dcache_lock 179 [<ffffffff80378274>] _atomic_dec_and_lock+0x34/0x54
24 dcache_lock 113 [<ffffffff802cc17b>] d_alloc+0x19a/0x1eb
25 dcache_lock 99 [<ffffffff802ca0dc>] d_rehash+0x1b/0x44
26 dcache_lock 104 [<ffffffff802cbca0>] d_instantiate+0x36/0x8a
27 -----------
28 dcache_lock 192 [<ffffffff80378274>] _atomic_dec_and_lock+0x34/0x54
29 dcache_lock 98 [<ffffffff802ca0dc>] d_rehash+0x1b/0x44
30 dcache_lock 72 [<ffffffff802cc17b>] d_alloc+0x19a/0x1eb
31 dcache_lock 112 [<ffffffff802cbca0>] d_instantiate+0x36/0x8a

This excerpt shows the first two lock class statistics. Line 01 shows the
output version - each time the format changes this will be updated. Line 02-04
show the header with column descriptions. Lines 05-10 and 13-18 show the actual
show the header with column descriptions. Lines 05-18 and 20-31 show the actual
statistics. These statistics come in two parts; the actual stats separated by a
short separator (line 08, 14) from the contention points.
short separator (line 08, 13) from the contention points.

The first lock (05-10) is a read/write lock, and shows two lines above the
The first lock (05-18) is a read/write lock, and shows two lines above the
short separator. The contention points don't match the column descriptors,
they have two: contentions and [<IP>] symbol.
they have two: contentions and [<IP>] symbol. The second set of contention
points are the points we're contending with.

The integer part of the time values is in us.

View the top contending locks:

Expand Down
14 changes: 14 additions & 0 deletions Documentation/markers.txt
Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,20 @@ a printk warning which identifies the inconsistency:

"Format mismatch for probe probe_name (format), marker (format)"

Another way to use markers is to simply define the marker without generating any
function call to actually call into the marker. This is useful in combination
with tracepoint probes in a scheme like this :

void probe_tracepoint_name(unsigned int arg1, struct task_struct *tsk);

DEFINE_MARKER_TP(marker_eventname, tracepoint_name, probe_tracepoint_name,
"arg1 %u pid %d");

notrace void probe_tracepoint_name(unsigned int arg1, struct task_struct *tsk)
{
struct marker *marker = &GET_MARKER(kernel_irq_entry);
/* write data to trace buffers ... */
}

* Probe / marker example

Expand Down
92 changes: 53 additions & 39 deletions Documentation/tracepoints.txt
Original file line number Diff line number Diff line change
Expand Up @@ -3,28 +3,30 @@
Mathieu Desnoyers


This document introduces Linux Kernel Tracepoints and their use. It provides
examples of how to insert tracepoints in the kernel and connect probe functions
to them and provides some examples of probe functions.
This document introduces Linux Kernel Tracepoints and their use. It
provides examples of how to insert tracepoints in the kernel and
connect probe functions to them and provides some examples of probe
functions.


* Purpose of tracepoints

A tracepoint placed in code provides a hook to call a function (probe) that you
can provide at runtime. A tracepoint can be "on" (a probe is connected to it) or
"off" (no probe is attached). When a tracepoint is "off" it has no effect,
except for adding a tiny time penalty (checking a condition for a branch) and
space penalty (adding a few bytes for the function call at the end of the
instrumented function and adds a data structure in a separate section). When a
tracepoint is "on", the function you provide is called each time the tracepoint
is executed, in the execution context of the caller. When the function provided
ends its execution, it returns to the caller (continuing from the tracepoint
site).
A tracepoint placed in code provides a hook to call a function (probe)
that you can provide at runtime. A tracepoint can be "on" (a probe is
connected to it) or "off" (no probe is attached). When a tracepoint is
"off" it has no effect, except for adding a tiny time penalty
(checking a condition for a branch) and space penalty (adding a few
bytes for the function call at the end of the instrumented function
and adds a data structure in a separate section). When a tracepoint
is "on", the function you provide is called each time the tracepoint
is executed, in the execution context of the caller. When the function
provided ends its execution, it returns to the caller (continuing from
the tracepoint site).

You can put tracepoints at important locations in the code. They are
lightweight hooks that can pass an arbitrary number of parameters,
which prototypes are described in a tracepoint declaration placed in a header
file.
which prototypes are described in a tracepoint declaration placed in a
header file.

They can be used for tracing and performance accounting.

Expand All @@ -42,14 +44,16 @@ In include/trace/subsys.h :

#include <linux/tracepoint.h>

DEFINE_TRACE(subsys_eventname,
DECLARE_TRACE(subsys_eventname,
TPPTOTO(int firstarg, struct task_struct *p),
TPARGS(firstarg, p));

In subsys/file.c (where the tracing statement must be added) :

#include <trace/subsys.h>

DEFINE_TRACE(subsys_eventname);

void somefct(void)
{
...
Expand All @@ -61,31 +65,41 @@ Where :
- subsys_eventname is an identifier unique to your event
- subsys is the name of your subsystem.
- eventname is the name of the event to trace.
- TPPTOTO(int firstarg, struct task_struct *p) is the prototype of the function
called by this tracepoint.
- TPARGS(firstarg, p) are the parameters names, same as found in the prototype.

Connecting a function (probe) to a tracepoint is done by providing a probe
(function to call) for the specific tracepoint through
register_trace_subsys_eventname(). Removing a probe is done through
unregister_trace_subsys_eventname(); it will remove the probe sure there is no
caller left using the probe when it returns. Probe removal is preempt-safe
because preemption is disabled around the probe call. See the "Probe example"
section below for a sample probe module.

The tracepoint mechanism supports inserting multiple instances of the same
tracepoint, but a single definition must be made of a given tracepoint name over
all the kernel to make sure no type conflict will occur. Name mangling of the
tracepoints is done using the prototypes to make sure typing is correct.
Verification of probe type correctness is done at the registration site by the
compiler. Tracepoints can be put in inline functions, inlined static functions,
and unrolled loops as well as regular functions.

The naming scheme "subsys_event" is suggested here as a convention intended
to limit collisions. Tracepoint names are global to the kernel: they are
considered as being the same whether they are in the core kernel image or in
modules.
- TPPTOTO(int firstarg, struct task_struct *p) is the prototype of the
function called by this tracepoint.

- TPARGS(firstarg, p) are the parameters names, same as found in the
prototype.

Connecting a function (probe) to a tracepoint is done by providing a
probe (function to call) for the specific tracepoint through
register_trace_subsys_eventname(). Removing a probe is done through
unregister_trace_subsys_eventname(); it will remove the probe.

tracepoint_synchronize_unregister() must be called before the end of
the module exit function to make sure there is no caller left using
the probe. This, and the fact that preemption is disabled around the
probe call, make sure that probe removal and module unload are safe.
See the "Probe example" section below for a sample probe module.

The tracepoint mechanism supports inserting multiple instances of the
same tracepoint, but a single definition must be made of a given
tracepoint name over all the kernel to make sure no type conflict will
occur. Name mangling of the tracepoints is done using the prototypes
to make sure typing is correct. Verification of probe type correctness
is done at the registration site by the compiler. Tracepoints can be
put in inline functions, inlined static functions, and unrolled loops
as well as regular functions.

The naming scheme "subsys_event" is suggested here as a convention
intended to limit collisions. Tracepoint names are global to the
kernel: they are considered as being the same whether they are in the
core kernel image or in modules.

If the tracepoint has to be used in kernel modules, an
EXPORT_TRACEPOINT_SYMBOL_GPL() or EXPORT_TRACEPOINT_SYMBOL() can be
used to export the defined tracepoints.

* Probe / tracepoint example

Expand Down
6 changes: 4 additions & 2 deletions Documentation/tracers/mmiotrace.txt
Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,7 @@ $ echo mmiotrace > /debug/tracing/current_tracer
$ cat /debug/tracing/trace_pipe > mydump.txt &
Start X or whatever.
$ echo "X is up" > /debug/tracing/trace_marker
$ echo none > /debug/tracing/current_tracer
$ echo nop > /debug/tracing/current_tracer
Check for lost events.


Expand Down Expand Up @@ -66,7 +66,7 @@ which action. It is recommended to place descriptive markers about what you
do.

Shut down mmiotrace (requires root privileges):
$ echo none > /debug/tracing/current_tracer
$ echo nop > /debug/tracing/current_tracer
The 'cat' process exits. If it does not, kill it by issuing 'fg' command and
pressing ctrl+c.

Expand All @@ -81,7 +81,9 @@ are:
$ cat /debug/tracing/trace_entries
gives you a number. Approximately double this number and write it back, for
instance:
$ echo 0 > /debug/tracing/tracing_enabled
$ echo 128000 > /debug/tracing/trace_entries
$ echo 1 > /debug/tracing/tracing_enabled
Then start again from the top.

If you are doing a trace for a driver project, e.g. Nouveau, you should also
Expand Down
1 change: 1 addition & 0 deletions arch/arm/mach-pxa/include/mach/pxafb.h
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@
#define LCD_CONN_TYPE(_x) ((_x) & 0x0f)
#define LCD_CONN_WIDTH(_x) (((_x) >> 4) & 0x1f)

#define LCD_TYPE_MASK 0xf
#define LCD_TYPE_UNKNOWN 0
#define LCD_TYPE_MONO_STN 1
#define LCD_TYPE_MONO_DSTN 2
Expand Down
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