kernel/tools/perf/Documentation/perf-diff.txt, branch linux-4.17.y

perf diff: Add -q/--quiet option

2017-02-20T14:47:08Z

The -q/--quiet option is to suppress any message. Sometimes users just want to see the numbers and it can be used for that case. Committer notes: Before: # perf diff | head -10 Failed to open /tmp/perf-6678.map, continuing without symbols Failed to open /tmp/perf-6678.map, continuing without symbols Failed to open /tmp/perf-2646.map, continuing without symbols # Event 'cycles' # # Baseline Delta Abs Shared Object Symbol # ........ ......... .......................... ............................................ # 5.36% -1.76% [kernel.vmlinux] [k] intel_idle 2.80% +1.48% firefox [.] 0x00000000000101fe 57.12% -1.25% libxul.so [.] 0x00000000009bea92 1.36% -1.11% [kernel.vmlinux] [k] __schedule 4.26% -1.00% perf-6678.map [.] 0x00007fac4b0e9320 After: # perf diff -q | head -10 5.36% -1.76% [kernel.vmlinux] [k] intel_idle 2.80% +1.48% firefox [.] 0x00000000000101fe 57.12% -1.25% libxul.so [.] 0x00000000009bea92 1.36% -1.11% [kernel.vmlinux] [k] __schedule 4.26% -1.00% perf-6678.map [.] 0x00007fac4b0e9320 1.86% +0.95% [kernel.vmlinux] [k] update_blocked_averages 0.80% -0.70% [kernel.vmlinux] [k] native_sched_clock 0.74% -0.58% [kernel.vmlinux] [k] native_write_msr 0.76% -0.56% qemu-system-x86_64 [.] 0x00000000002395c0 +0.54% libpulsecommon-10.0.so [.] 0x000000000002d91b # Signed-off-by: Namhyung Kim Suggested-and-Tested-by: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Peter Zijlstra Cc: kernel-team@lge.com Link: http://lkml.kernel.org/r/20170217081742.17417-5-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf diff: Change default setting to "delta-abs"

2017-02-13T17:29:38Z

The "delta-abs" compute method will show most changed entries on top. So users can easily see how much effect between the data. Note that it also changes the default of -o option to 1 in order to apply the compute method. To see original-style (sorted by baseline) use -o 0 option. Signed-off-by: Namhyung Kim Cc: Jiri Olsa Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20170210161856.18422-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf diff: Add diff.compute config option

2017-02-13T17:29:37Z

The diff.compute config variable is to set the default compute method of perf diff command (-c option). Possible values 'delta' (default), 'delta-abs', 'ratio' and 'wdiff'. Signed-off-by: Namhyung Kim Cc: Jiri Olsa Cc: Peter Zijlstra Cc: Taeung Song Link: http://lkml.kernel.org/r/20170210073614.24584-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf diff: Add diff.order config option

2017-02-13T17:29:37Z

In many cases, I need to look at differences between two data so I often used the -o option to sort the result base on the difference first. It'd be nice to have a config option to set it by default. The diff.order config option is to set the default value of -o/--order option. Signed-off-by: Namhyung Kim Cc: Jiri Olsa Cc: Peter Zijlstra Cc: Taeung Song Link: http://lkml.kernel.org/r/20170210073614.24584-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf diff: Add 'delta-abs' compute method

2017-02-13T17:29:36Z

The 'delta-abs' compute method is same as 'delta' but shows entries with bigger absolute delta first instead of sorting numerically. This is only useful together with -o option. Below is default output (-c delta): $ perf diff -o 1 -c delta | grep -v ^# | head 42.22% +4.97% [kernel.kallsyms] [k] cfb_imageblit 0.62% +1.23% [kernel.kallsyms] [k] mutex_lock +1.15% [kernel.kallsyms] [k] copy_user_generic_string 2.40% +0.95% [kernel.kallsyms] [k] bit_putcs 0.31% +0.79% [kernel.kallsyms] [k] link_path_walk +0.64% [kernel.kallsyms] [k] kmem_cache_alloc 0.00% +0.57% [kernel.kallsyms] [k] __rcu_read_unlock +0.45% [kernel.kallsyms] [k] alloc_set_pte 0.16% +0.45% [kernel.kallsyms] [k] menu_select +0.41% ld-2.24.so [.] do_lookup_x Now with 'delta-abs' it shows entries have bigger delta value either positive or negative. $ perf diff -o 1 -c delta-abs | grep -v ^# | head 42.22% +4.97% [kernel.kallsyms] [k] cfb_imageblit 12.72% -3.01% [kernel.kallsyms] [k] intel_idle 9.72% -1.31% [unknown] [.] 0x0000000000411343 0.62% +1.23% [kernel.kallsyms] [k] mutex_lock 2.40% +0.95% [kernel.kallsyms] [k] bit_putcs 0.31% +0.79% [kernel.kallsyms] [k] link_path_walk 1.35% -0.71% [kernel.kallsyms] [k] smp_call_function_single 0.00% +0.57% [kernel.kallsyms] [k] __rcu_read_unlock 0.16% +0.45% [kernel.kallsyms] [k] menu_select 0.72% -0.44% [kernel.kallsyms] [k] lookup_fast Signed-off-by: Namhyung Kim Cc: Jiri Olsa Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20170210073614.24584-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

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

2016-03-30T14:14:08Z

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

2015-03-24T16:01:54Z

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

2015-02-27T13:08:38Z

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

2014-10-15T20:39:02Z

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

2014-05-21T09:45:34Z

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