linux.git/tools/perf/util/thread.c, branch v5.3-rc2

perf tools: Use list_del_init() more thorougly

2019-07-09T13:13:27+00:00

To allow for destructors to check if they're operating on a object still
in a list, and to avoid going from use after free list entries into
still valid, or even also other already removed from list entries.

Cc: Adrian Hunter 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: https://lkml.kernel.org/n/tip-deh17ub44atyox3j90e6rksu@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

tools lib: Adopt zalloc()/zfree() from tools/perf

2019-07-09T13:13:26+00:00

Eroding a bit more the tools/perf/util/util.h hodpodge header.

Cc: Adrian Hunter 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: https://lkml.kernel.org/n/tip-natazosyn9rwjka25tvcnyi0@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

Merge remote-tracking branch 'tip/perf/core' into perf/urgent

2019-07-08T16:06:57+00:00

To pick up fixes.

Signed-off-by: Arnaldo Carvalho de Melo

perf thread: Allow references to thread objects after machine__exit()

2019-07-06T17:29:32+00:00

Threads are created when we either synthesize PERF_RECORD_FORK events
for pre-existing threads or when we receive PERF_RECORD_FORK events from
the kernel as new threads get created.

We then keep them in machine->threads[].entries rb trees till when we
receive a PERF_RECORD_EXIT, i.e. that thread terminated.

The thread object has a reference count that is grabbed when, for
instance, we keep that thread referenced in struct hist_entry, in 'perf
report' and 'perf top'.

When we receive a PERF_RECORD_EXIT we remove the thread object from the
rb tree and move it to the corresponding machine->threads[].dead list,
then we do a thread__put(), dropping the reference we had for keeping it
in the rb tree.

In thread__put() we were assuming that when the reference count hit zero
we should remove it from the dead list by simply doing a
list_del_init(&thread->node).

That works well when all the thread lifetime is during the machine that
has the list heads lifetime, since we know that we can do the
list_del_init() and it will update the 'dead' list_head.

But in 'perf sched lat' we were doing:

    machine__new() (via perf_session__new)

    process events, grabbing refcounts to keep those thread objects
    in 'perf sched' local data structures.

    machine__exit() (via perf_session__delete) which would delete the
    'dead' list heads.

    And then doing the final thread__put() for the refcounts 'perf sched'
    rightfully obtained for keeping those thread object references.

    b00m, since thread__put() would do the list_del_init() touching
    a dead dead list head.

Fix it by removing all the dead threads from machine->threads[].dead at
machine__exit(), since whatever is there should have refcounts taken by
things like 'perf sched lat', and make thread__put() check if the thread
is in a linked list before removing it from that list.

Reported-by: Wei Li 
Link: https://lkml.kernel.org/r/20190508143648.8153-1-liwei391@huawei.com
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Zhipeng Xie 
Link: https://lkml.kernel.org/r/20190704194355.GI10740@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Remove const from thread read accessors

2019-05-28T21:37:43+00:00

The namespaces and comm fields of a thread are protected by rwsem and
require write access for it.  So it ended up using a cast to remove
the const qualifier.  Let's get rid of the const then.

Signed-off-by: Namhyung Kim 
Suggested-by: Arnaldo Carvalho de Melo 
Cc: Hari Bathini 
Cc: Jiri Olsa 
Cc: Krister Johansen 
Link: http://lkml.kernel.org/r/20190527061149.168640-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf namespace: Protect reading thread's namespace

2019-05-28T12:52:23+00:00

It seems that the current code lacks holding the namespace lock in
thread__namespaces().  Otherwise it can see inconsistent results.

Signed-off-by: Namhyung Kim 
Cc: Hari Bathini 
Cc: Jiri Olsa 
Cc: Krister Johansen 
Link: http://lkml.kernel.org/r/20190522053250.207156-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Speed up report for perf compiled with linwunwind

2019-05-15T19:36:46+00:00

When compiled with libunwind, perf does some preparatory work when
processing side-band events. This is not needed when report actually
don't unwind dwarf callchains, so it's disabled with
dwarf_callchain_users bool.

However we could move that check to higher level and shield more
unwanted code for normal report processing, giving us following speed up
on kernel build profile:

Before:

  $ perf record make -j40
  ...
  $ ll ../../perf.data
  -rw-------. 1 jolsa jolsa 461783932 Apr 26 09:11 perf.data
  $ perf stat -e cycles:u,instructions:u perf report -i perf.data > out

   Performance counter stats for 'perf report -i perf.data':

    78,669,920,155      cycles:u
    99,076,431,951      instructions:u            #    1.26  insn per cycle

      55.382823668 seconds time elapsed

      27.512341000 seconds user
      27.712871000 seconds sys

After:

  $ perf stat -e cycles:u,instructions:u perf report -i perf.data > out

   Performance counter stats for 'perf report -i perf.data':

    59,626,798,904      cycles:u
    88,583,575,849      instructions:u            #    1.49  insn per cycle

      21.296935559 seconds time elapsed

      20.010191000 seconds user
       1.202935000 seconds sys

The speed is higher with profile having many side-band events,
because these trigger libunwind preparatory code.

This does not apply for perf compiled with libdw for dwarf unwind,
only for build with libunwind.

Signed-off-by: Jiri Olsa 
Cc: Alexander Shishkin 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20190426073804.17238-1-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf thread: Generalize function to copy from thread addr space from intel-bts code

2019-03-06T20:55:35+00:00

Add a utility function to fetch executable code. Convert one
user over to it. There are more places doing that, but they
do significantly different actions, so they are not
easy to fit into a single library function.

Committer changes:

. No need to cast around, make 'buf' be a void pointer.

. Rename it to thread__memcpy() to reflect the fact it is about copying
  a chunk of memory from a thread, i.e. from its address space.

. No need to have it in a separate object file, move it to thread.[ch]

. Check the return of map__load(), the original code didn't do it, but
  since we're moving this around, check that as well.

Signed-off-by: Andi Kleen 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: https://lkml.kernel.org/r/20190305144758.12397-2-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Add missing include for symbols.h

2019-02-06T13:00:38+00:00

Several places were using definitions found in symbols.h but not
including it, getting it by sheer luck from some other headers that now
are in the process of removing that include because they don't need it
or because simply having struct forward declarations is enough, fix it.

Cc: Adrian Hunter 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Link: https://lkml.kernel.org/n/tip-xbcvvx296d70kpg9wb0qmeq9@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Support 'srccode' output

2018-12-17T17:57:07+00:00

When looking at PT or brstackinsn traces with 'perf script' it can be
very useful to see the source code. This adds a simple facility to print
them with 'perf script', if the information is available through dwarf

  % perf record ...
  % perf script -F insn,ip,sym,srccode
  ...

            4004c6 main
  5               for (i = 0; i < 10000000; i++)
             4004cd main
  5               for (i = 0; i < 10000000; i++)
             4004c6 main
  5               for (i = 0; i < 10000000; i++)
             4004cd main
  5               for (i = 0; i < 10000000; i++)
             4004cd main
  5               for (i = 0; i < 10000000; i++)
             4004cd main
  5               for (i = 0; i < 10000000; i++)
             4004cd main
  5               for (i = 0; i < 10000000; i++)
             4004cd main
  5               for (i = 0; i < 10000000; i++)
             4004b3 main
  6                       v++;

  % perf record -b ...
  % perf script -F insn,ip,sym,srccode,brstackinsn

  ...
         main+22:
          0000000000400543        insn: e8 ca ff ff ff            # PRED
  |18                     f1();
          f1:
          0000000000400512        insn: 55
  |10       {
          0000000000400513        insn: 48 89 e5
          0000000000400516        insn: b8 00 00 00 00
  |11             f2();
          000000000040051b        insn: e8 d6 ff ff ff            # PRED
          f2:
          00000000004004f6        insn: 55
  |5        {
          00000000004004f7        insn: 48 89 e5
          00000000004004fa        insn: 8b 05 2c 0b 20 00
  |6              c = a / b;
          0000000000400500        insn: 8b 0d 2a 0b 20 00
          0000000000400506        insn: 99
          0000000000400507        insn: f7 f9
          0000000000400509        insn: 89 05 29 0b 20 00
          000000000040050f        insn: 90
  |7        }
          0000000000400510        insn: 5d
          0000000000400511        insn: c3                        # PRED
          f1+14:
          0000000000400520        insn: b8 00 00 00 00
  |12             f2();
          0000000000400525        insn: e8 cc ff ff ff            # PRED
          f2:
          00000000004004f6        insn: 55
  |5        {
          00000000004004f7        insn: 48 89 e5
          00000000004004fa        insn: 8b 05 2c 0b 20 00
  |6              c = a / b;

Not supported for callchains currently, would need some layout changes
there.

Committer notes:

Fixed the build on Alpine Linux (3.4 .. 3.8) by addressing this
warning:

  In file included from util/srccode.c:19:0:
  /usr/include/sys/fcntl.h:1:2: error: #warning redirecting incorrect #include  to  [-Werror=cpp]
   #warning redirecting incorrect #include  to 
    ^~~~~~~
  cc1: all warnings being treated as errors

Signed-off-by: Andi Kleen 
Tested-by: Jiri Olsa 
Link: http://lkml.kernel.org/r/20181204001848.24769-1-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo