linux-toradex.git/tools/perf/Documentation/perf-diff.txt, branch v4.8-rc2

perf tools: Make -f/--force option documentation consistent across tools

2016-03-30T14:14:08+00:00

Signed-off-by: Jiri Olsa 
Cc: Andi Kleen 
Cc: David Ahern 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Link: http://lkml.kernel.org/r/1458823940-24583-6-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf diff: Add kallsyms option

2015-03-24T16:01:54+00:00

Required for off-box analysis to convert kernel addresses.

Signed-off-by: David Ahern 
Cc: Jiri Olsa 
Link: http://lkml.kernel.org/r/1427212317-7018-1-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo

perf diff: Support for different binaries

2015-02-27T13:08:38+00:00

Currently, the perf diff only works with same binaries. That's because
it compares the symbol start address. It doesn't work if the perf.data
comes from different binaries. This patch matches the symbol names.

Actually, perf diff once intended to compare the symbol names.  The
commit as below can look for a pair by name.

604c5c92972d (perf diff: Change the default sort order to "dso,symbol")
However, at that time, perf diff used a global list of dsos. That means
the binaries which has same name can only be loaded once. That's a
problem for comparing different binaries.

For example, we have an old binary and an updated binary. They very
likely have same name and most of the functions, so only dsos from old
binary will be loaded. When processing the data from updated binary,
perf still use the symbol information from old binary. That's wrong.

Then the commit as below used IP to replace symbol name.
9c443dfdd31e ("perf diff: Fix support for all --sort combinations")
>From that time, perf diff starts to compare the symbol address.

The global dsos is discarded from a patch in 2010.
a1645ce12adb ("perf: 'perf kvm' tool for monitoring guest performance
from host")
However, at that time, perf diff already compared by address. So perf
diff cannot work for different binaries as well.

This patch actually rolls back the perf diff to original design. The
document is also changed, so everybody knows the original design is to
compare the symbol names.

Here are some examples:

The only difference between example_v1.c and example_v2.c is the
location of f2 and f3. There is no change in behavior, but the previous
perf diff display the wrong differential profile.

example_v1.c
noinline void f3(void)
{
        volatile int i;
        for (i = 0; i < 10000;) {

                if(i%2)
                        i++;
                else
                        i++;
        }
}

noinline void f2(void)
{
        volatile int a = 100, b, c;
        for (b = 0; b < 10000; b++)
                c = a * b;

}

noinline void f1(void)
{
                f2();
                f3();
}

int main()
{
        int i;
        for (i = 0; i < 100000; i++)
                f1();
}

example_v2.c
noinline void f2(void)
{
        volatile int a = 100, b, c;
        for (b = 0; b < 10000; b++)
                c = a * b;
}

noinline void f3(void)
{
        volatile int i;
        for (i = 0; i < 10000;) {
                if(i%2)
                        i++;
                else
                        i++;
        }
}

noinline void f1(void)
{
                f2();
                f3();
}

int main()
{
        int i;
        for (i = 0; i < 100000; i++)
                f1();
}

[lk@localhost perf_diff]$ gcc example_v1.c -o example
[lk@localhost perf_diff]$ perf record -o example_v1.data ./example
[ perf record: Woken up 4 times to write data ]
[ perf record: Captured and wrote 0.813 MB example_v1.data (~35522 samples) ]

[lk@localhost perf_diff]$ gcc example_v2.c -o example
[lk@localhost perf_diff]$ perf record -o example_v2.data ./example
[ perf record: Woken up 4 times to write data ]
[ perf record: Captured and wrote 0.824 MB example_v2.data (~36015 samples) ]

Old perf diff result:

[lk@localhost perf_diff]$ perf diff example_v1.data example_v2.data
 Event 'cycles'
 Baseline    Delta  Shared Object     Symbol
 ........  .......  ................  ...............................

                     [kernel.vmlinux]  [k] __perf_event_task_sched_out
     0.00%           [kernel.vmlinux]  [k] apic_timer_interrupt
                     [kernel.vmlinux]  [k] idle_cpu
                     [kernel.vmlinux]  [k] intel_pstate_timer_func
                     [kernel.vmlinux]  [k] native_read_msr_safe
     0.00%           [kernel.vmlinux]  [k] native_read_tsc
     0.00%           [kernel.vmlinux]  [k] native_write_msr_safe
                     [kernel.vmlinux]  [k] ntp_tick_length
     0.00%           [kernel.vmlinux]  [k] rb_erase
     0.00%           [kernel.vmlinux]  [k] tick_sched_timer
     0.00%           [kernel.vmlinux]  [k] unmap_single_vma
     0.00%           [kernel.vmlinux]  [k] update_wall_time
     0.00%           example           [.] f1
    46.24%           example           [.] f2
    53.71%   -7.55%  example           [.] f3
            +53.81%  example           [.] f3
     0.02%           example           [.] main

New perf diff result:

[lk@localhost perf_diff]$ perf diff example_v1.data example_v2.data
                     [kernel.vmlinux]  [k] __perf_event_task_sched_out
     0.00%           [kernel.vmlinux]  [k] apic_timer_interrupt
                     [kernel.vmlinux]  [k] idle_cpu
                     [kernel.vmlinux]  [k] intel_pstate_timer_func
                     [kernel.vmlinux]  [k] native_read_msr_safe
     0.00%           [kernel.vmlinux]  [k] native_read_tsc
     0.00%           [kernel.vmlinux]  [k] native_write_msr_safe
                     [kernel.vmlinux]  [k] ntp_tick_length
     0.00%           [kernel.vmlinux]  [k] rb_erase
     0.00%           [kernel.vmlinux]  [k] tick_sched_timer
     0.00%           [kernel.vmlinux]  [k] unmap_single_vma
     0.00%           [kernel.vmlinux]  [k] update_wall_time
     0.00%           example           [.] f1
    46.24%   -0.08%  example           [.] f2
    53.71%   +0.11%  example           [.] f3
     0.02%           example           [.] main

Signed-off-by: Kan Liang 
Acked-by: Jiri Olsa 
Acked-by: Namhyung Kim 
Cc: Andi Kleen 
Link: http://lkml.kernel.org/r/1423460384-11645-1-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf Documentation: Fix typos in perf/Documentation

2014-10-15T20:39:02+00:00

This patch fix spelling typos found in tool/perf/Documentation.

Signed-off-by: Masanari Iida 
Acked-by: Randy Dunlap 
Cc: Ingo Molnar 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Randy Dunlap 
Link: http://lkml.kernel.org/r/1410275930-17207-1-git-send-email-standby24x7@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Allow hpp fields to be sort keys

2014-05-21T09:45:34+00:00

Add overhead{,_sys,_us,_guest_sys,_guest_us}, sample and period sort
keys so that they can be selected with --sort/-s option.

  $ perf report -s period,comm --stdio
  ...
  # Overhead        Period          Command
  # ........  ............  ...............
  #
      47.06%           152          swapper
      13.93%            45  qemu-system-arm
      12.38%            40         synergys
       3.72%            12          firefox
       2.48%             8            xchat

Signed-off-by: Namhyung Kim 
Acked-by: Ingo Molnar 
Link: http://lkml.kernel.org/r/1400480762-22852-9-git-send-email-namhyung@kernel.org
Signed-off-by: Jiri Olsa

perf diff: Add --percentage option

2014-04-16T15:16:03+00:00

The --percentage option is for controlling overhead percentage
displayed.  It can only receive either of "relative" or "absolute" and
affects -c delta output only.

For more information, please see previous commit same thing done to
"perf report".

Signed-off-by: Namhyung Kim 
Link: http://lkml.kernel.org/r/1397145720-8063-5-git-send-email-namhyung@kernel.org
Signed-off-by: Jiri Olsa

perf diff: Add generic order option for compute sorting

2013-07-12T16:54:16+00:00

Adding option 'o' to allow sorting based on the input file number. By
default (without -o option) the output is sorted on baseline.

Also removing '+' sorting support from -c option, because it's not
needed anymore.

Signed-off-by: Jiri Olsa 
Reviewed-by: Namhyung Kim 
Cc: Corey Ashford 
Cc: Frederic Weisbecker 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-l7dvhgt0azm7yiqg3fbn4dxw@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf diff: Update perf diff documentation for multiple data comparison

2013-07-12T16:54:13+00:00

Updating perf diff documentation to include multiple perf data files
comparison.

Signed-off-by: Jiri Olsa 
Reviewed-by: Namhyung Kim 
Cc: Corey Ashford 
Cc: Frederic Weisbecker 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-tr6su3wfm20k2m5npjggyvtw@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf diff: Remove displacement output option

2012-12-09T11:46:07+00:00

It seems not very useful, because it's possible and event more convenient to
lookup related symbol by name. Also the output value for both 'baseline' and
'new' data is quite apparent from diff output.

And above all it complicates hist code factoring ;)

Ditching out PERF_HPP__DISPL column with related output functions.

Suggested-by: Arnaldo Carvalho de Melo 
Signed-off-by: Jiri Olsa 
Cc: Corey Ashford 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Ingo Molnar 
Cc: Namhyung Kim 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Link: http://lkml.kernel.org/r/20121206132228.GB1080@krava.brq.redhat.com
Signed-off-by: Arnaldo Carvalho de Melo

perf diff: Add -F option to display formula for computation

2012-10-05T17:13:36+00:00

Adding -F option to display the formula for specified computation.

This is mainly to facilitate debugging, but can be useful anyway.

Signed-off-by: Jiri Olsa 
Cc: Andi Kleen 
Cc: Corey Ashford 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1349448287-18919-7-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo