This means the user can't access /proc/kallsyms, for instance, because
/proc/sys/kernel/kptr_restrict is set to 1.
Instead leave the ref_reloc_sym as NULL and code using it will cope.
This allows 'perf trace' to work on such systems for !root, the only
issue would be when trying to resolve kernel symbols, which happens,
for instance, in some libtracevent plugins. A warning for that case
will be provided in the next patch in this series.
Noticed in Ubuntu 16.04, that comes with kptr_restrict=1.
Reported-by: Milian Wolff <milian.wolff@kdab.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-knpu3z4iyp2dxpdfm798fac4@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Currently only the task-clock event updates the runtime_nsec so it
cannot show the metric when using cpu-clock events. However cpu clock
works basically same as task-clock, so no need to not update the runtime
IMHO.
Before:
# perf stat -a -e cpu-clock,context-switches,page-faults,cycles sleep 0.1
Performance counter stats for 'system wide':
1217.759506 cpu-clock (msec)
93 context-switches
61 page-faults
18,958,022 cycles
0.101393794 seconds time elapsed
After:
Performance counter stats for 'system wide':
1220.471884 cpu-clock (msec) # 12.013 CPUs utilized
118 context-switches # 0.097 K/sec
59 page-faults # 0.048 K/sec
17,941,247 cycles # 0.015 GHz
0.101594777 seconds time elapsed
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1463119263-5569-2-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When an IP with an unresolved symbol occurs in the callchain more than
once (ie. recursion), then duplicate symbols can be created because
the callchain nodes are never updated after they are first created.
To fix this issue we call dso__find_symbol whenever we encounter a NULL
symbol, in case we already added a symbol at that IP since we started
traversing the callchain.
This change prevents duplicate symbols from being exported when duplicate
IPs are present in the callchain.
Signed-off-by: Chris Phlipot <cphlipot0@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1462937209-6032-5-git-send-email-cphlipot0@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Remove the call to map_ip() to adjust al.addr, because it has already
been called when assembling the callchain, in:
thread__resolve_callchain_sample(perf_sample)
add_callchain_ip(ip = perf_sample->callchain->ips[j])
thread__find_addr_location(addr = ip)
thread__find_addr_map(addr) {
al->addr = addr
if (al->map)
al->addr = al->map->map_ip(al->map, al->addr);
}
Calling it a second time can result in incorrect addresses being used.
This can have effects such as duplicate symbols being created and
exported.
Signed-off-by: Chris Phlipot <cphlipot0@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1462937209-6032-4-git-send-email-cphlipot0@gmail.com
[ Show the callchain where it is done, to help reviewing this change down the line ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The current method for inserting symbols is to use the symbols__insert()
function. However symbols__insert() does not update the dso symbol
cache. This causes problems in the following scenario:
1. symbol not found at addr using dso__find_symbol
2. symbol inserted at addr using the existing symbols__insert function
3. symbol still not found at addr using dso__find_symbol() because cache isn't
updated. This is undesired behavior.
The undesired behavior in (3) is addressed by creating a new function,
dso__insert_symbol() to both insert the symbol and update the symbol
cache if necessary.
If dso__insert_symbol() is used in (2) instead of symbols__insert(),
then the undesired behavior in (3) is avoided.
Signed-off-by: Chris Phlipot <cphlipot0@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1462937209-6032-2-git-send-email-cphlipot0@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:
User visible changes:
- Recording 'dwarf' callchains do not need DWARF unwinding support (He Kuang)
- Print recently added perf_event_attr.write_backward bit flag in -vv
verbose mode (Arnaldo Carvalho de Melo)
- Fix incorrect python db-export error message in 'perf script' (Chris Phlipot)
- Fix handling of zero-length symbols (Chris Phlipot)
- perf stat: Scale values by unit before metrics (Andi Kleen)
Infrastructure changes:
- Rewrite strbuf not to die(), making tools using it to check its
return value instead (Masami Hiramatsu)
- Support reading from backward ring buffer, add a 'perf test' entry
for it (Wang Nan)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Make alias handler and sq_quote_argv to check the return value of strbuf
APIs.
In sq_quote_argv() calls die(), but this fix handles strbuf failure as a
special case and returns to caller, since the caller - handle_alias()
also has to check the return value of other strbuf APIs and those checks
can be merged to one if() statement.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160510054725.6158.84597.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This change introduces a fix to symbols__find, so that it is able to
find symbols of length zero (where start == end).
The current code has the following problem:
- The current implementation of symbols__find is unable to find any symbols
of length zero.
- The db-export framework explicitly creates zero length symbols at
locations where no symbol currently exists.
The combination of the two above behaviors results in behavior similar
to the example below.
1. addr_location is created for a sample, but symbol is unable to be
resolved.
2. db export creates an "unknown" symbol of length zero at that address
and inserts it into the dso.
3. A new sample comes in at the same address, but symbol__find is unable
to find the zero length symbol, so it is still unresolved.
4. db export sees the symbol is unresolved, and allocated a duplicate
symbol, even though it already did this in step 2.
This behavior continues every time an address without symbol information
is seen, which causes a very large number of these symbols to be
allocated.
The effect of this fix can be observed by looking at the contents of an
exported database before/after the fix (generated with
scripts/python/export-to-postgresql.py)
Ex.
BEFORE THE CHANGE:
example_db=# select count(*) from symbols;
count
--------
900213
(1 row)
example_db=# select count(*) from symbols where symbols.name='unknown';
count
--------
897355
(1 row)
example_db=# select count(*) from symbols where symbols.name!='unknown';
count
-------
2858
(1 row)
AFTER THE CHANGE:
example_db=# select count(*) from symbols;
count
-------
25217
(1 row)
example_db=# select count(*) from symbols where name='unknown';
count
-------
22359
(1 row)
example_db=# select count(*) from symbols where name!='unknown';
count
-------
2858
(1 row)
Signed-off-by: Chris Phlipot <cphlipot0@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1462612620-25008-1-git-send-email-cphlipot0@gmail.com
[ Moved the test to later in the rb_tree tests, as this not the likely case ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Now we can see if it is set when using verbose mode in various tools,
such as 'perf test':
# perf test -vv back
45: Test backward reading from ring buffer :
--- start ---
<SNIP>
------------------------------------------------------------
perf_event_attr:
type 2
size 112
config 0x98
{ sample_period, sample_freq } 1
sample_type IP|TID|TIME|CPU|PERIOD|RAW
disabled 1
mmap 1
comm 1
task 1
sample_id_all 1
exclude_guest 1
mmap2 1
comm_exec 1
write_backward 1
------------------------------------------------------------
sys_perf_event_open: pid 20911 cpu -1 group_fd -1 flags 0x8
<SNIP>
---- end ----
Test backward reading from ring buffer: Ok
#
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-kxv05kv9qwl5of7rzfeiiwbv@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This test checks reading from backward ring buffer.
Test result:
# ~/perf test 'ring buffer'
45: Test backward reading from ring buffer : Ok
The test case is a while loop which calls prctl(PR_SET_NAME) multiple
times. Each prctl should issue 2 events: one PERF_RECORD_SAMPLE, one
PERF_RECORD_COMM.
The first round creates a relative large ring buffer (256 pages). It can
afford all events. Read from it and check the count of each type of
events.
The second round creates a small ring buffer (1 page) and makes it
overwritable. Check the correctness of the buffer.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1462758471-89706-3-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
klogctl can fail and return -ve len, so check for this and
return NULL to avoid passing a (size_t)-1 to malloc.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Update the export-to-postgresql.py to support the newly introduced
callchain export.
callchains are added into the existing call_paths table and can now
be associated with samples when the "callpaths" commandline option
is used with the script.
Ex.:
$ perf script -s export-to-postgresql.py example_db all callchains
Includes the following changes to enable callchain export via the python export
APIs:
- Add the "callchains" commandline option, which is used to enable
callchain export by setting the perf_db_export_callchains global
- Add perf_db_export_callchains checks for call_path table creation
and population.
- Add call_path_id to samples_table to conform with the new API
example usage and output using a small test app:
test_app.c:
volatile int x = 0;
void inc_x_loop()
{
int i;
for(i=0; i<100000000; i++)
x++;
}
void a()
{
inc_x_loop();
}
void b()
{
inc_x_loop();
}
int main()
{
a();
b();
return 0;
}
example usage:
$ gcc -g -O0 test_app.c
$ perf record --call-graph=dwarf ./a.out
[ perf record: Woken up 77 times to write data ]
[ perf record: Captured and wrote 19.373 MB perf.data (2404 samples) ]
$ perf script -s scripts/python/export-to-postgresql.py
example_db all callchains
$ psql example_db
example_db=#
SELECT
(SELECT name FROM symbols WHERE id = cps.symbol_id) as symbol,
(SELECT name FROM symbols WHERE id =
(SELECT symbol_id from call_paths where id = cps.parent_id))
as parent_symbol,
sum(period) as event_count
FROM samples join call_paths as cps on call_path_id = cps.id
GROUP BY cps.id,evsel_id
ORDER BY event_count DESC
LIMIT 5;
symbol | parent_symbol | event_count
------------------+--------------------------+-------------
inc_x_loop | a | 734250982
inc_x_loop | b | 731028057
unknown | unknown | 1335858
task_tick_fair | scheduler_tick | 1238842
update_wall_time | tick_do_update_jiffies64 | 650373
(5 rows)
The above data shows total "self time" in cycles for each call path that was
sampled. It is intended to demonstrate how it accounts separately for the two
ways to reach the "inc_x_loop" function(via "a" and "b"). Recursive common
table expressions can be used as well to get cumulative time spent in a
function as well, but that is beyond the scope of this basic example.
Signed-off-by: Chris Phlipot <cphlipot0@gmail.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1461831551-12213-7-git-send-email-cphlipot0@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This change allows python scripts to be able to utilize the recent
changes to the db export api allowing the export of call_paths derived
from sampled callchains. These call paths are also now associated with
the samples from which they were derived.
- This feature is enabled by setting "perf_db_export_callchains" to true
- When enabled, samples that have callchain information will have the
callchains exported via call_path_table
- The call_path_id field is added to sample_table to enable association of
samples with the corresponding callchain stored in the call paths
table. A call_path_id of 0 will be exported if there is no
corresponding callchain.
- When "perf_db_export_callchains" and "perf_db_export_calls" are both
set to True, the call path root data structure will be shared. This
prevents duplicating of data and call path ids that would result from
building two separate call path trees in memory.
- The call_return_processor structure definition was relocated to the header
file to make its contents visible to db-export.c. This enables the
sharing of call path trees between the two features, as mentioned
above.
This change is visible to python scripts using the python db export api.
The change is backwards compatible with scripts written against the
previous API, assuming that the scripts model the sample_table function
after the one in export-to-postgresql.py script by allowing for
additional arguments to be added in the future. ie. using *x as the
final argument of the sample_table function.
Signed-off-by: Chris Phlipot <cphlipot0@gmail.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1461831551-12213-6-git-send-email-cphlipot0@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
