<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/kernel/trace/blktrace.c, branch v3.5-rc6</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>simple_open: automatically convert to simple_open()</title>
<updated>2012-04-05T22:25:50+00:00</updated>
<author>
<name>Stephen Boyd</name>
<email>sboyd@codeaurora.org</email>
</author>
<published>2012-04-05T21:25:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=234e340582901211f40d8c732afc49f0630ecf05'/>
<id>234e340582901211f40d8c732afc49f0630ecf05</id>
<content type='text'>
Many users of debugfs copy the implementation of default_open() when
they want to support a custom read/write function op.  This leads to a
proliferation of the default_open() implementation across the entire
tree.

Now that the common implementation has been consolidated into libfs we
can replace all the users of this function with simple_open().

This replacement was done with the following semantic patch:

&lt;smpl&gt;
@ open @
identifier open_f != simple_open;
identifier i, f;
@@
-int open_f(struct inode *i, struct file *f)
-{
(
-if (i-&gt;i_private)
-f-&gt;private_data = i-&gt;i_private;
|
-f-&gt;private_data = i-&gt;i_private;
)
-return 0;
-}

@ has_open depends on open @
identifier fops;
identifier open.open_f;
@@
struct file_operations fops = {
...
-.open = open_f,
+.open = simple_open,
...
};
&lt;/smpl&gt;

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Stephen Boyd &lt;sboyd@codeaurora.org&gt;
Cc: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Julia Lawall &lt;Julia.Lawall@lip6.fr&gt;
Acked-by: Ingo Molnar &lt;mingo@elte.hu&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Many users of debugfs copy the implementation of default_open() when
they want to support a custom read/write function op.  This leads to a
proliferation of the default_open() implementation across the entire
tree.

Now that the common implementation has been consolidated into libfs we
can replace all the users of this function with simple_open().

This replacement was done with the following semantic patch:

&lt;smpl&gt;
@ open @
identifier open_f != simple_open;
identifier i, f;
@@
-int open_f(struct inode *i, struct file *f)
-{
(
-if (i-&gt;i_private)
-f-&gt;private_data = i-&gt;i_private;
|
-f-&gt;private_data = i-&gt;i_private;
)
-return 0;
-}

@ has_open depends on open @
identifier fops;
identifier open.open_f;
@@
struct file_operations fops = {
...
-.open = open_f,
+.open = simple_open,
...
};
&lt;/smpl&gt;

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Stephen Boyd &lt;sboyd@codeaurora.org&gt;
Cc: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Julia Lawall &lt;Julia.Lawall@lip6.fr&gt;
Acked-by: Ingo Molnar &lt;mingo@elte.hu&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>switch debugfs to umode_t</title>
<updated>2012-01-04T03:54:56+00:00</updated>
<author>
<name>Al Viro</name>
<email>viro@zeniv.linux.org.uk</email>
</author>
<published>2011-07-24T08:33:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=f4ae40a6a50a98ac23d4b285f739455e926a473e'/>
<id>f4ae40a6a50a98ac23d4b285f739455e926a473e</id>
<content type='text'>
Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>kernel: Fix files explicitly needing EXPORT_SYMBOL infrastructure</title>
<updated>2011-10-31T23:30:05+00:00</updated>
<author>
<name>Paul Gortmaker</name>
<email>paul.gortmaker@windriver.com</email>
</author>
<published>2011-05-26T20:00:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=6e5fdeedca610df600aabc393c4b1f44b128fe49'/>
<id>6e5fdeedca610df600aabc393c4b1f44b128fe49</id>
<content type='text'>
These files were getting &lt;linux/module.h&gt; via an implicit non-obvious
path, but we want to crush those out of existence since they cost
time during compiles of processing thousands of lines of headers
for no reason.  Give them the lightweight header that just contains
the EXPORT_SYMBOL infrastructure.

Signed-off-by: Paul Gortmaker &lt;paul.gortmaker@windriver.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
These files were getting &lt;linux/module.h&gt; via an implicit non-obvious
path, but we want to crush those out of existence since they cost
time during compiles of processing thousands of lines of headers
for no reason.  Give them the lightweight header that just contains
the EXPORT_SYMBOL infrastructure.

Signed-off-by: Paul Gortmaker &lt;paul.gortmaker@windriver.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>blktrace: add FLUSH/FUA support</title>
<updated>2011-08-11T08:36:05+00:00</updated>
<author>
<name>Namhyung Kim</name>
<email>namhyung@gmail.com</email>
</author>
<published>2011-08-11T08:36:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=c09c47caedc9854d59378d6e34c989e51cfdd2b4'/>
<id>c09c47caedc9854d59378d6e34c989e51cfdd2b4</id>
<content type='text'>
Add FLUSH/FUA support to blktrace. As FLUSH precedes WRITE and/or
FUA follows WRITE, use the same 'F' flag for both cases and
distinguish them by their (relative) position. The end results
look like (other flags might be shown also):

 - WRITE:            W
 - WRITE_FLUSH:      FW
 - WRITE_FUA:        WF
 - WRITE_FLUSH_FUA:  FWF

Note that we reuse TC_BARRIER due to lack of bit space of act_mask
so that the older versions of blktrace tools will report flush
requests as barriers from now on.

Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Signed-off-by: Namhyung Kim &lt;namhyung@gmail.com&gt;
Reviewed-by: Jeff Moyer &lt;jmoyer@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add FLUSH/FUA support to blktrace. As FLUSH precedes WRITE and/or
FUA follows WRITE, use the same 'F' flag for both cases and
distinguish them by their (relative) position. The end results
look like (other flags might be shown also):

 - WRITE:            W
 - WRITE_FLUSH:      FW
 - WRITE_FUA:        WF
 - WRITE_FLUSH_FUA:  FWF

Note that we reuse TC_BARRIER due to lack of bit space of act_mask
so that the older versions of blktrace tools will report flush
requests as barriers from now on.

Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Frederic Weisbecker &lt;fweisbec@gmail.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Signed-off-by: Namhyung Kim &lt;namhyung@gmail.com&gt;
Reviewed-by: Jeff Moyer &lt;jmoyer@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: make unplug timer trace event correspond to the schedule() unplug</title>
<updated>2011-04-16T11:51:05+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>jaxboe@fusionio.com</email>
</author>
<published>2011-04-16T11:51:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=49cac01e1fa74174d72adb0e872504a7fefd7c01'/>
<id>49cac01e1fa74174d72adb0e872504a7fefd7c01</id>
<content type='text'>
It's a pretty close match to what we had before - the timer triggering
would mean that nobody unplugged the plug in due time, in the new
scheme this matches very closely what the schedule() unplug now is.
It's essentially the difference between an explicit unplug (IO unplug)
or an implicit unplug (timer unplug, we scheduled with pending IO
queued).

Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
It's a pretty close match to what we had before - the timer triggering
would mean that nobody unplugged the plug in due time, in the new
scheme this matches very closely what the schedule() unplug now is.
It's essentially the difference between an explicit unplug (IO unplug)
or an implicit unplug (timer unplug, we scheduled with pending IO
queued).

Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: fixup block IO unplug trace call</title>
<updated>2011-04-12T08:12:19+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>jaxboe@fusionio.com</email>
</author>
<published>2011-04-12T08:12:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=94b5eb28b41cc79d9713696e0005ae167b5afd1b'/>
<id>94b5eb28b41cc79d9713696e0005ae167b5afd1b</id>
<content type='text'>
It was removed with the on-stack plugging, readd it and track the
depth of requests added when flushing the plug.

Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
It was removed with the on-stack plugging, readd it and track the
depth of requests added when flushing the plug.

Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: remove block_unplug_timer() trace point</title>
<updated>2011-04-12T08:06:33+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>jaxboe@fusionio.com</email>
</author>
<published>2011-04-12T08:06:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=d9c97833179036408e53ef5f3f5c7eaf781769bc'/>
<id>d9c97833179036408e53ef5f3f5c7eaf781769bc</id>
<content type='text'>
We no longer have an unplug timer running, so no point in keeping
the trace point.

Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We no longer have an unplug timer running, so no point in keeping
the trace point.

Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>blktrace: Use rq-&gt;cmd_flags directly in blk_add_trace_rq.</title>
<updated>2011-03-11T19:11:59+00:00</updated>
<author>
<name>Tao Ma</name>
<email>boyu.mt@taobao.com</email>
</author>
<published>2011-03-11T19:11:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=805f6b5e1cbfedfb9b3d354013e7f4b13a79270f'/>
<id>805f6b5e1cbfedfb9b3d354013e7f4b13a79270f</id>
<content type='text'>
In blk_add_trace_rq, we only chose the minor 2 bits from
request's cmd_flags and did some check for discard.
so most of other flags(e.g, REQ_SYNC) are missing.

For example, with a sync write after blkparse we get:
  8,16   1        1     0.001776503  7509  A  WS 1349632 + 1024 &lt;- (8,17) 1347584
  8,16   1        2     0.001776813  7509  Q  WS 1349632 + 1024 [dd]
  8,16   1        3     0.001780395  7509  G  WS 1349632 + 1024 [dd]
  8,16   1        5     0.001783186  7509  I   W 1349632 + 1024 [dd]
  8,16   1       11     0.001816987  7509  D   W 1349632 + 1024 [dd]
  8,16   0        2     0.006218192     0  C   W 1349632 + 1024 [0]

Since now we have integrated the flags of both bio and request,
it is safe to pass rq-&gt;cmd_flags directly to __blk_add_trace.

With this patch, after a sync write we get:
  8,16   1        1     0.001776900  5425  A  WS 1189888 + 1024 &lt;- (8,17) 1187840
  8,16   1        2     0.001777179  5425  Q  WS 1189888 + 1024 [dd]
  8,16   1        3     0.001780797  5425  G  WS 1189888 + 1024 [dd]
  8,16   1        5     0.001783402  5425  I  WS 1189888 + 1024 [dd]
  8,16   1       11     0.001817468  5425  D  WS 1189888 + 1024 [dd]
  8,16   0        2     0.005640709     0  C  WS 1189888 + 1024 [0]

Signed-off-by: Tao Ma &lt;boyu.mt@taobao.com&gt;
Acked-by: Jeff Moyer &lt;jmoyer@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In blk_add_trace_rq, we only chose the minor 2 bits from
request's cmd_flags and did some check for discard.
so most of other flags(e.g, REQ_SYNC) are missing.

For example, with a sync write after blkparse we get:
  8,16   1        1     0.001776503  7509  A  WS 1349632 + 1024 &lt;- (8,17) 1347584
  8,16   1        2     0.001776813  7509  Q  WS 1349632 + 1024 [dd]
  8,16   1        3     0.001780395  7509  G  WS 1349632 + 1024 [dd]
  8,16   1        5     0.001783186  7509  I   W 1349632 + 1024 [dd]
  8,16   1       11     0.001816987  7509  D   W 1349632 + 1024 [dd]
  8,16   0        2     0.006218192     0  C   W 1349632 + 1024 [0]

Since now we have integrated the flags of both bio and request,
it is safe to pass rq-&gt;cmd_flags directly to __blk_add_trace.

With this patch, after a sync write we get:
  8,16   1        1     0.001776900  5425  A  WS 1189888 + 1024 &lt;- (8,17) 1187840
  8,16   1        2     0.001777179  5425  Q  WS 1189888 + 1024 [dd]
  8,16   1        3     0.001780797  5425  G  WS 1189888 + 1024 [dd]
  8,16   1        5     0.001783402  5425  I  WS 1189888 + 1024 [dd]
  8,16   1       11     0.001817468  5425  D  WS 1189888 + 1024 [dd]
  8,16   0        2     0.005640709     0  C  WS 1189888 + 1024 [0]

Signed-off-by: Tao Ma &lt;boyu.mt@taobao.com&gt;
Acked-by: Jeff Moyer &lt;jmoyer@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>blktrace: Remove blk_fill_rwbs_rq.</title>
<updated>2011-03-03T15:53:20+00:00</updated>
<author>
<name>Tao Ma</name>
<email>boyu.mt@taobao.com</email>
</author>
<published>2011-03-03T15:53:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=2d3a8497f8cc5aca14b722cd37d51f6c15ff9f74'/>
<id>2d3a8497f8cc5aca14b722cd37d51f6c15ff9f74</id>
<content type='text'>
If we enable trace events to trace block actions, We use
blk_fill_rwbs_rq to analyze the corresponding actions
in request's cmd_flags, but we only choose the minor 2 bits
from it, so most of other flags(e.g, REQ_SYNC) are missing.
For example, with a sync write we get:
write_test-2409  [001]   160.013869: block_rq_insert: 3,64 W 0 () 258135 + =
8 [write_test]

Since now we have integrated the flags of both bio and request,
it is safe to pass rq-&gt;cmd_flags directly to blk_fill_rwbs and
blk_fill_rwbs_rq isn't needed any more.

With this patch, after a sync write we get:
write_test-2417  [000]   226.603878: block_rq_insert: 3,64 WS 0 () 258135 +=
 8 [write_test]

Signed-off-by: Tao Ma &lt;boyu.mt@taobao.com&gt;
Acked-by: Jeff Moyer &lt;jmoyer@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
If we enable trace events to trace block actions, We use
blk_fill_rwbs_rq to analyze the corresponding actions
in request's cmd_flags, but we only choose the minor 2 bits
from it, so most of other flags(e.g, REQ_SYNC) are missing.
For example, with a sync write we get:
write_test-2409  [001]   160.013869: block_rq_insert: 3,64 W 0 () 258135 + =
8 [write_test]

Since now we have integrated the flags of both bio and request,
it is safe to pass rq-&gt;cmd_flags directly to blk_fill_rwbs and
blk_fill_rwbs_rq isn't needed any more.

With this patch, after a sync write we get:
write_test-2417  [000]   226.603878: block_rq_insert: 3,64 WS 0 () 258135 +=
 8 [write_test]

Signed-off-by: Tao Ma &lt;boyu.mt@taobao.com&gt;
Acked-by: Jeff Moyer &lt;jmoyer@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>blktrace: Don't output messages if NOTIFY isn't set.</title>
<updated>2011-01-19T15:25:02+00:00</updated>
<author>
<name>Tao Ma</name>
<email>boyu.mt@taobao.com</email>
</author>
<published>2011-01-19T02:51:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=490da40d82b31c0562d3f5edb37810f492ca1c34'/>
<id>490da40d82b31c0562d3f5edb37810f492ca1c34</id>
<content type='text'>
Now if we enable blktrace, cfq has too many messages output to the
trace buffer. It is fine if we don't specify any action mask.
But if I do like this:
blktrace /dev/sdb -a issue -a complete -o - | blkparse -i -
I only want to see 'D' and 'C', while with the following command
dd if=/mnt/ocfs2/test of=/dev/null bs=4k count=1 iflag=direct

I will get(with a 2.6.37 vanilla kernel):
  8,16   0        0     0.000000000     0  m   N cfq3805 alloced
  8,16   0        0     0.000004126     0  m   N cfq3805 insert_request
  8,16   0        0     0.000004884     0  m   N cfq3805 add_to_rr
  8,16   0        0     0.000008417     0  m   N cfq workload slice:300
  8,16   0        0     0.000009557     0  m   N cfq3805 set_active wl_prio:0 wl_type:2
  8,16   0        0     0.000010640     0  m   N cfq3805 fifo=          (null)
  8,16   0        0     0.000011193     0  m   N cfq3805 dispatch_insert
  8,16   0        0     0.000012221     0  m   N cfq3805 dispatched a request
  8,16   0        0     0.000012802     0  m   N cfq3805 activate rq, drv=1
  8,16   0        1     0.000013181  3805  D   R 114759 + 8 [dd]
  8,16   0        2     0.000164244     0  C   R 114759 + 8 [0]
  8,16   0        0     0.000167997     0  m   N cfq3805 complete rqnoidle 0
  8,16   0        0     0.000168782     0  m   N cfq3805 set_slice=100
  8,16   0        0     0.000169874     0  m   N cfq3805 arm_idle: 8 group_idle: 0
  8,16   0        0     0.000170189     0  m   N cfq schedule dispatch
  8,16   0        0     0.000397938     0  m   N cfq3805 slice expired t=0
  8,16   0        0     0.000399763     0  m   N cfq3805 sl_used=1 disp=1 charge=1 iops=0 sect=8
  8,16   0        0     0.000400227     0  m   N cfq3805 del_from_rr
  8,16   0        0     0.000400882     0  m   N cfq3805 put_queue

See, there are 19 lines while I only need 2. I don't think it is
appropriate for a user.

So this patch will disable any messages if the BLK_TC_NOTIFY isn't set.
Now the output for the same command will look like:
  8,16   0        1     0.000000000  4908  D   R 114759 + 8 [dd]
  8,16   0        2     0.000146827     0  C   R 114759 + 8 [0]

Yes, it is what I want to see.

Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Jeff Moyer &lt;jmoyer@redhat.com&gt;
Signed-off-by: Tao Ma &lt;boyu.mt@taobao.com&gt;
Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Now if we enable blktrace, cfq has too many messages output to the
trace buffer. It is fine if we don't specify any action mask.
But if I do like this:
blktrace /dev/sdb -a issue -a complete -o - | blkparse -i -
I only want to see 'D' and 'C', while with the following command
dd if=/mnt/ocfs2/test of=/dev/null bs=4k count=1 iflag=direct

I will get(with a 2.6.37 vanilla kernel):
  8,16   0        0     0.000000000     0  m   N cfq3805 alloced
  8,16   0        0     0.000004126     0  m   N cfq3805 insert_request
  8,16   0        0     0.000004884     0  m   N cfq3805 add_to_rr
  8,16   0        0     0.000008417     0  m   N cfq workload slice:300
  8,16   0        0     0.000009557     0  m   N cfq3805 set_active wl_prio:0 wl_type:2
  8,16   0        0     0.000010640     0  m   N cfq3805 fifo=          (null)
  8,16   0        0     0.000011193     0  m   N cfq3805 dispatch_insert
  8,16   0        0     0.000012221     0  m   N cfq3805 dispatched a request
  8,16   0        0     0.000012802     0  m   N cfq3805 activate rq, drv=1
  8,16   0        1     0.000013181  3805  D   R 114759 + 8 [dd]
  8,16   0        2     0.000164244     0  C   R 114759 + 8 [0]
  8,16   0        0     0.000167997     0  m   N cfq3805 complete rqnoidle 0
  8,16   0        0     0.000168782     0  m   N cfq3805 set_slice=100
  8,16   0        0     0.000169874     0  m   N cfq3805 arm_idle: 8 group_idle: 0
  8,16   0        0     0.000170189     0  m   N cfq schedule dispatch
  8,16   0        0     0.000397938     0  m   N cfq3805 slice expired t=0
  8,16   0        0     0.000399763     0  m   N cfq3805 sl_used=1 disp=1 charge=1 iops=0 sect=8
  8,16   0        0     0.000400227     0  m   N cfq3805 del_from_rr
  8,16   0        0     0.000400882     0  m   N cfq3805 put_queue

See, there are 19 lines while I only need 2. I don't think it is
appropriate for a user.

So this patch will disable any messages if the BLK_TC_NOTIFY isn't set.
Now the output for the same command will look like:
  8,16   0        1     0.000000000  4908  D   R 114759 + 8 [dd]
  8,16   0        2     0.000146827     0  C   R 114759 + 8 [0]

Yes, it is what I want to see.

Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Jeff Moyer &lt;jmoyer@redhat.com&gt;
Signed-off-by: Tao Ma &lt;boyu.mt@taobao.com&gt;
Signed-off-by: Jens Axboe &lt;jaxboe@fusionio.com&gt;
</pre>
</div>
</content>
</entry>
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