The flat callchain mode is to print all chains in a single, simple
hierarchy so make it easy to see.
Currently perf report --tui doesn't show flat callchains properly. With
flat callchains, only leaf nodes are added to the final rbtree so it
should show entries in parent nodes. To do that, add parent_val list to
struct callchain_node and show them along with the (normal) val list.
For example, consider following callchains with '-g graph'.
$ perf report -g graph
- 39.93% swapper [kernel.vmlinux] [k] intel_idle
intel_idle
cpuidle_enter_state
cpuidle_enter
call_cpuidle
- cpu_startup_entry
28.63% start_secondary
- 11.30% rest_init
start_kernel
x86_64_start_reservations
x86_64_start_kernel
Before:
$ perf report -g flat
- 39.93% swapper [kernel.vmlinux] [k] intel_idle
28.63% start_secondary
- 11.30% rest_init
start_kernel
x86_64_start_reservations
x86_64_start_kernel
After:
$ perf report -g flat
- 39.93% swapper [kernel.vmlinux] [k] intel_idle
- 28.63% intel_idle
cpuidle_enter_state
cpuidle_enter
call_cpuidle
cpu_startup_entry
start_secondary
- 11.30% intel_idle
cpuidle_enter_state
cpuidle_enter
call_cpuidle
cpu_startup_entry
start_kernel
x86_64_start_reservations
x86_64_start_kernel
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1447047946-1691-8-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Now -g/--call-graph option supports how to display callchain values.
Possible values are 'percent', 'period' and 'count'. The percent is
same as before and it's the default behavior. The period displays the
raw period value rather than the percentage. The count displays the
number of occurrences.
$ perf report --no-children --stdio -g percent
...
39.93% swapper [kernel.vmlinux] [k] intel_idel
|
---intel_idle
cpuidle_enter_state
cpuidle_enter
call_cpuidle
cpu_startup_entry
|
|--28.63%-- start_secondary
|
--11.30%-- rest_init
$ perf report --no-children --show-total-period --stdio -g period
...
39.93% 13018705 swapper [kernel.vmlinux] [k] intel_idel
|
---intel_idle
cpuidle_enter_state
cpuidle_enter
call_cpuidle
cpu_startup_entry
|
|--9334403-- start_secondary
|
--3684302-- rest_init
$ perf report --no-children --show-nr-samples --stdio -g count
...
39.93% 80 swapper [kernel.vmlinux] [k] intel_idel
|
---intel_idle
cpuidle_enter_state
cpuidle_enter
call_cpuidle
cpu_startup_entry
|
|--57-- start_secondary
|
--23-- rest_init
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1447047946-1691-6-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Add new call chain option (-g) 'folded' to print callchains in a line.
The callchains are separated by semicolons, and preceded by (absolute)
percent values and a space.
For example, the following 20 lines can be printed in 3 lines with the
folded output mode:
$ perf report -g flat --no-children | grep -v ^# | head -20
60.48% swapper [kernel.vmlinux] [k] intel_idle
54.60%
intel_idle
cpuidle_enter_state
cpuidle_enter
call_cpuidle
cpu_startup_entry
start_secondary
5.88%
intel_idle
cpuidle_enter_state
cpuidle_enter
call_cpuidle
cpu_startup_entry
rest_init
start_kernel
x86_64_start_reservations
x86_64_start_kernel
$ perf report -g folded --no-children | grep -v ^# | head -3
60.48% swapper [kernel.vmlinux] [k] intel_idle
54.60% intel_idle;cpuidle_enter_state;cpuidle_enter;call_cpuidle;cpu_startup_entry;start_secondary
5.88% intel_idle;cpuidle_enter_state;cpuidle_enter;call_cpuidle;cpu_startup_entry;rest_init;start_kernel;x86_64_start_reservations;x86_64_start_kernel
This mode is supported only for --stdio now and intended to be used by
some scripts like in FlameGraphs[1]. Support for other UI might be
added later.
[1] http://www.brendangregg.com/FlameGraphs/cpuflamegraphs.html
Requested-and-Tested-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1447047946-1691-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Currently 'perf top --call-graph' option is same as 'perf record'. But
'perf top' also need to receive display options in 'perf report'. To do
that, change parse_callchain_report_opt() to allow record options too.
Now perf top can receive display options like below:
$ perf top --call-graph
Error: option `call-graph' requires a value
Usage: perf top [<options>]
--call-graph
<mode[,dump_size],output_type,min_percent[,print_limit],call_order[,branch]>
setup and enables call-graph (stack chain/backtrace)
recording: fp dwarf lbr, output_type (graph, flat,
fractal, or none), min percent threshold, optional
print limit, callchain order, key (function or
address), add branches
$ perf top --call-graph callee,graph,fp
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Chandler Carruth <chandlerc@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1445495330-25416-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Currently branch stacks can be only shown as edge histograms for
individual branches. I never found this display particularly useful.
This implements an alternative mode that creates histograms over
complete branch traces, instead of individual branches, similar to how
normal callgraphs are handled. This is done by putting it in front of
the normal callgraph and then using the normal callgraph histogram
infrastructure to unify them.
This way in complex functions we can understand the control flow that
lead to a particular sample, and may even see some control flow in the
caller for short functions.
Example (simplified, of course for such simple code this is usually not
needed), please run this after the whole patchkit is in, as at this
point in the patch order there is no --branch-history, that will be
added in a patch after this one:
tcall.c:
volatile a = 10000, b = 100000, c;
__attribute__((noinline)) f2()
{
c = a / b;
}
__attribute__((noinline)) f1()
{
f2();
f2();
}
main()
{
int i;
for (i = 0; i < 1000000; i++)
f1();
}
% perf record -b -g ./tsrc/tcall
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.044 MB perf.data (~1923 samples) ]
% perf report --no-children --branch-history
...
54.91% tcall.c:6 [.] f2 tcall
|
|--65.53%-- f2 tcall.c:5
| |
| |--70.83%-- f1 tcall.c:11
| | f1 tcall.c:10
| | main tcall.c:18
| | main tcall.c:18
| | main tcall.c:17
| | main tcall.c:17
| | f1 tcall.c:13
| | f1 tcall.c:13
| | f2 tcall.c:7
| | f2 tcall.c:5
| | f1 tcall.c:12
| | f1 tcall.c:12
| | f2 tcall.c:7
| | f2 tcall.c:5
| | f1 tcall.c:11
| |
| --29.17%-- f1 tcall.c:12
| f1 tcall.c:12
| f2 tcall.c:7
| f2 tcall.c:5
| f1 tcall.c:11
| f1 tcall.c:10
| main tcall.c:18
| main tcall.c:18
| main tcall.c:17
| main tcall.c:17
| f1 tcall.c:13
| f1 tcall.c:13
| f2 tcall.c:7
| f2 tcall.c:5
| f1 tcall.c:12
The default output is unchanged.
This is only implemented in perf report, no change to record or anywhere
else.
This adds the basic code to report:
- add a new "branch" option to the -g option parser to enable this mode
- when the flag is set include the LBR into the callstack in machine.c.
The rest of the history code is unchanged and doesn't know the
difference between LBR entry and normal call entry.
- detect overlaps with the callchain
- remove small loop duplicates in the LBR
Current limitations:
- The LBR flags (mispredict etc.) are not shown in the history
and LBR entries have no special marker.
- It would be nice if annotate marked the LBR entries somehow
(e.g. with arrows)
v2: Various fixes.
v3: Merge further patches into this one. Fix white space.
v4: Improve manpage. Address review feedback.
v5: Rename functions. Better error message without -g. Fix crash without
-b.
v6: Rebase
v7: Rebase. Use NO_ENTRY in memset.
v8: Port to latest tip. Move add_callchain_ip to separate
patch. Skip initial entries in callchain. Minor cleanups.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1415844328-4884-3-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
For lbr-as-callgraph we need to see the line number in the history,
because many LBR entries can be in a single function, and just
showing the same function name many times is not useful.
When the history code is configured to sort by address, also try to
resolve the address to a file:srcline and display this in the browser.
If that doesn't work still display the address.
This can be also useful without LBRs for understanding which call in a large
function (or in which inlined function) called something else.
Contains fixes from Namhyung Kim
v2: Refactor code into common function
v3: Fix GTK build
v4: Rebase
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1415844328-4884-7-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When a new callchain child branch matches an existing one in the rbtree,
the comparison of its first entry is performed twice:
1) From append_chain_children() on branch lookup
2) If 1) reports a match, append_chain() then compares all entries of
the new branch against the matching node in the rbtree, and this
comparison includes the first entry of the new branch again.
Lets shortcut this by performing the whole comparison only from
append_chain() which then returns the result of the comparison between
the first entry of the new branch and the iterating node in the rbtree.
If the first entry matches, the lookup on the current level of siblings
stops and propagates to the children of the matching nodes.
This results in less comparisons performed by the CPU.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1389713836-13375-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Current collapse stage has a scalability problem which can be reproduced
easily with a parallel kernel build.
This is because it needs to traverse every children of callchains
linearly during the collapse/merge stage.
Converting it to a rbtree reduced the overhead significantly.
On my 400MB perf.data file which recorded with make -j32 kernel build:
$ time perf --no-pager report --stdio > /dev/null
before:
real 6m22.073s
user 6m18.683s
sys 0m0.706s
after:
real 0m20.780s
user 0m19.962s
sys 0m0.689s
During the perf report the overhead on append_chain_children went down
from 96.69% to 18.16%:
- 18.16% perf perf [.] append_chain_children
- append_chain_children
- 77.48% append_chain_children
+ 69.79% merge_chain_branch
- 22.96% append_chain_children
+ 67.44% merge_chain_branch
+ 30.15% append_chain_children
+ 2.41% callchain_append
+ 7.25% callchain_append
+ 12.26% callchain_append
+ 10.22% merge_chain_branch
+ 11.58% perf perf [.] dso__find_symbol
+ 8.02% perf perf [.] sort__comm_cmp
+ 5.48% perf libc-2.17.so [.] malloc_consolidate
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1381468543-25334-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
With programs with very large functions it can be useful to distinguish
the callgraph nodes on more than just function names. So for example if
you have multiple calls to the same function, it ends up being separate
nodes in the chain.
This patch adds a new key field to the callgraph options, that allows
comparing nodes on functions (as today, default) and addresses.
Longer term it would be nice to also handle src lines, but that would
need more changes and address is a reasonable proxy for it today.
I right now reference the global params, as there was no simple way to
register a params pointer.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-0uskktybf0e7wrnoi5e9b9it@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
A sweep of the kernel for regex "kcalloc(sizeof" turned up 2 reversed
args, fixed in commit d3d09e1820 ("EDAC:
Fix kcalloc argument order") and also fixed in the networking commit
a1b1add07f ("gro: Fix kcalloc argument
order").
I know that was the regex used, because on seeing the 1st of these
changes, I wondered "how many other instances of this are there" and I
happened to just use "calloc(sizeof" as a regex and it in turn found
these additional reversed args instances in the perf code.
In the kcalloc cases, the changes are cosmetic, since the numbers are
simply multiplied. I had no desire to go data mining in userspace to
see if the same thing held true there, however.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1359594349-25912-1-git-send-email-paul.gortmaker@windriver.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
perf defines both __used and __unused variables to use for marking
unused variables. The variable __used is defined to
__attribute__((__unused__)), which contradicts the kernel definition to
__attribute__((__used__)) for new gcc versions. On Android, __used is
also defined in system headers and this leads to warnings like: warning:
'__used__' attribute ignored
__unused is not defined in the kernel and is not a standard definition.
If __unused is included everywhere instead of __used, this leads to
conflicts with glibc headers, since glibc has a variables with this name
in its headers.
The best approach is to use __maybe_unused, the definition used in the
kernel for __attribute__((unused)). In this way there is only one
definition in perf sources (instead of 2 definitions that point to the
same thing: __used and __unused) and it works on both Linux and Android.
This patch simply replaces all instances of __used and __unused with
__maybe_unused.
Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1347315303-29906-7-git-send-email-irina.tirdea@intel.com
[ committer note: fixed up conflict with a116e05 in builtin-sched.c ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The callchains are fed with an array of a fixed size.
As a result we iterate over each callchains three times:
- 1st to resolve symbols
- 2nd to filter out context boundaries
- 3rd for the insertion into the tree
This also involves some pairs of memory allocation/deallocation
everytime we insert a callchain, for the filtered out array of
addresses and for the array of symbols that comes along.
Instead, feed the callchains through a linked list with persistent
allocations. It brings several pros like:
- Merge the 1st and 2nd iterations in one. That was possible before
but in a way that would involve allocating an array slightly taller
than necessary because we don't know in advance the number of context
boundaries to filter out.
- Much lesser allocations/deallocations. The linked list keeps
persistent empty entries for the next usages and is extendable at
will.
- Makes it easier for multiple sources of callchains to feed a
stacktrace together. This is deemed to pave the way for cfi based
callchains wherein traditional frame pointer based kernel
stacktraces will precede cfi based user ones, producing an overall
callchain which size is hardly predictable. This requirement
makes the static array obsolete and makes a linked list based
iterator a much more flexible fit.
Basic testing on a big perf file containing callchains (~ 176 MB)
has shown a throughput gain of about 11% with perf report.
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1294977121-5700-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
If we sort the histograms by comm, which is the default,
we need to merge some of them, typically different thread
histograms of a same process, or just same comm. But during
this merge, we forgot to merge callchains.
So imagine we have three threads (tids: 1000, 1001, 1002) that
belong to comm "foo".
tid 1000 got 100 events
tid 1001 got 10 events
tid 1002 got 3 events
Once we merge these histograms to get a per comm result, we'll
finally get:
"foo" got 113 events
The problem is if we merge 1000 and 1001 histograms into 1002, then
the end merge result, wrt callchains, will be only callchains that
belong to 1002.
This is because we haven't handled callchains in the merge. Only those
from one of the threads inside a common comm survive.
It means during this merge, we can lose a lot of callchains.
Fix this by implementing callchains merge and apply it on histograms
that collapse.
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
In order to implement callchains collapsing, we need to keep
track of the maximum depth in a histogram tree of callchains.
This way we'll avoid allocating an arbitrary temporary buffer
size on callchain merge time.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Christoph Hellwig <hch@infradead.org>
Hists have their hits increased by the event period. And this
period based counting is the foundation of all the stats in
perf report.
But callchains still use the raw number of hits, without taking
the period into account. So when we compute the percentage,
absolute based percentages are totally broken, and relative ones
too in the first parent level. Because we pass the number of events
muliplied by their period as the total number of hits to the
callchain filtering, while callchains expect this number to be
the number of raw hits.
perf report -g graph was simply not working, showing no graph unless
the min percent was zero. And even there the percentage of the
branches was always 0. And may be fractal filtering was broken on
the first branch level too.
flat also was broken, but it was hidden because of other breakages.
Anyway fix this by counting using periods on callchains.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
We were still using the pathname found on the MMAP event, that could not
be the one we used when recording, so use the build-id cache for that,
only falling back to use the pathname in the MMAP event if no build-ids
are available.
With this we now also are able to do secure, seamless offline annotation.
Example:
[root@doppio linux-2.6-tip]# perf report -g none -v 2> /dev/null | head -10
8.12% Xorg /usr/lib64/libpixman-1.so.0.14.0 0x0000000000026d02 B [.] pixman_rasterize_edges
4.68% firefox /usr/lib64/xulrunner-1.9.1/libxul.so 0x00000000005dbdba B [.] 0x000000005dbdba
3.70% swapper /lib/modules/2.6.34-rc6/build/vmlinux 0xffffffff81022cea ! [k] read_hpet
2.96% init /lib/modules/2.6.34-rc6/build/vmlinux 0xffffffff81022cea ! [k] read_hpet
2.73% swapper /lib/modules/2.6.34-rc6/build/vmlinux 0xffffffff8100a738 ! [k] mwait_idle_with_hints
[root@doppio linux-2.6-tip]# perf annotate -v pixman_rasterize_edges 2>&1 | grep Executing
Executing: objdump --start-address=0x000000371ce26670 --stop-address=0x000000371ce2709f -dS /root/.debug/.build-id/bd/6ac5199137aaeb279f864717d8d061477466c1|grep -v /root/.debug/.build-id/bd/6ac5199137aaeb279f864717d8d061477466c1|expand
[root@doppio linux-2.6-tip]# perf buildid-list | grep libpixman-1.so.0.14.0
bd6ac5199137aaeb279f864717d8d061477466c1 /usr/lib64/libpixman-1.so.0.14.0
[root@doppio linux-2.6-tip]#
Reported-by: Stephane Eranian <eranian@google.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
