Messages in this thread | | | Date | Wed, 5 Jun 2019 13:44:24 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH v2 0/7] perf diff: diff cycles at basic block level |
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On Mon, Jun 03, 2019 at 10:36:10PM +0800, Jin Yao wrote: > In some cases small changes in hot loops can show big differences. > But it's difficult to identify these differences. > > perf diff currently can only diff symbols (functions). We can also expand > it to diff cycles of individual programs blocks as reported by timed LBR. > This would allow to identify changes in specific code accurately.
can't compile on Fedora 30
builtin-diff.c: In function ‘block_cycles_diff_cmp’: builtin-diff.c:544:6: error: absolute value function ‘abs’ given an argument of type ‘s64’ {aka ‘long int’} but has parameter of type ‘int’ which may cause truncation of value [-Werror=absolute-value] 544 | l = abs(left->diff.cycles); | ^~~ builtin-diff.c:545:6: error: absolute value function ‘abs’ given an argument of type ‘s64’ {aka ‘long int’} but has parameter of type ‘int’ which may cause truncation of value [-Werror=absolute-value] 545 | r = abs(right->diff.cycles); | ^~~
[jolsa@krava perf]$ gcc --version gcc (GCC) 9.1.1 20190503 (Red Hat 9.1.1-1)
jirka
> > With this patch set, for example, > > # perf record -b ./div > # perf record -b ./div > # perf diff -s cycles > > # Event 'cycles' > # > # Baseline Block cycles diff [start:end] Shared Object Symbol > # ........ .................................... ................ .................................... > # > 49.03% -9 [ 4ef: 520] div [.] main > 49.03% 0 [ 4e8: 4ea] div [.] main > 49.03% 0 [ 4ef: 500] div [.] main > 49.03% 0 [ 4ef: 51c] div [.] main > 49.03% 0 [ 4ef: 535] div [.] main > 18.82% 0 [ 3ac40: 3ac4d] libc-2.23.so [.] __random_r > 18.82% 0 [ 3ac40: 3ac5c] libc-2.23.so [.] __random_r > 18.82% 0 [ 3ac40: 3ac76] libc-2.23.so [.] __random_r > 18.82% 0 [ 3ac40: 3ac88] libc-2.23.so [.] __random_r > 18.82% 0 [ 3ac90: 3ac9c] libc-2.23.so [.] __random_r > 16.29% -8 [ 3aac0: 3aac0] libc-2.23.so [.] __random > 16.29% 0 [ 3aac0: 3aad2] libc-2.23.so [.] __random > 16.29% 0 [ 3aae0: 3aae7] libc-2.23.so [.] __random > 16.29% 0 [ 3ab03: 3ab0f] libc-2.23.so [.] __random > 16.29% 0 [ 3ab14: 3ab1b] libc-2.23.so [.] __random > 16.29% 0 [ 3ab28: 3ab2e] libc-2.23.so [.] __random > 16.29% 0 [ 3ab4a: 3ab53] libc-2.23.so [.] __random > 8.11% 0 [ 640: 644] div [.] compute_flag > 8.11% 0 [ 649: 659] div [.] compute_flag > 5.46% 0 [ 3af60: 3af60] libc-2.23.so [.] rand > 5.46% 0 [ 3af60: 3af64] libc-2.23.so [.] rand > 2.25% 0 [ 490: 490] div [.] rand@plt > 0.01% 26 [ c00a27: c00a27] [kernel.vmlinux] [k] native_irq_return_iret > 0.00% -157 [ 2bf9f2: 2bfa63] [kernel.vmlinux] [k] update_blocked_averages > 0.00% -56 [ 2bf980: 2bf9d3] [kernel.vmlinux] [k] update_blocked_averages > 0.00% 48 [ 2bf934: 2bf942] [kernel.vmlinux] [k] update_blocked_averages > 0.00% 3 [ 2bfb38: 2bfb67] [kernel.vmlinux] [k] update_blocked_averages > > The 'cycles' is a new perf-diff computation selection, which enables > the displaying of cycles difference of same program basic block amongst > two perf.data. The program basic block is the code block between two > branches in a function. > > v2: > --- > Keep standard perf diff format. > > Following is the v1 output. > > # perf diff --basic-block > > # Cycles diff Basic block (start:end) > # ........... ....................... > # > -208 hrtimer_interrupt (30b9e0:30ba42) > -157 update_blocked_averages (2bf9f2:2bfa63) > -126 interrupt_entry (c00880:c0093a) > -86 hrtimer_interrupt (30bb29:30bb32) > -74 hrtimer_interrupt (30ba65:30bac4) > -56 update_blocked_averages (2bf980:2bf9d3) > 48 update_blocked_averages (2bf934:2bf942) > -35 native_write_msr (267900:26790b) > 26 native_irq_return_iret (c00a27:c00a27) > 22 rcu_check_callbacks (2febb6:2febdc) > -21 __hrtimer_run_queues (30b220:30b2a3) > 19 pvclock_gtod_notify (14ba0:14c1b) > -18 task_tick_fair (2c5d29:2c5d41) > > Jin Yao (7): > perf util: Create block_info structure > perf util: Add block_info in hist_entry > perf diff: Check if all data files with branch stacks > perf diff: Use hists to manage basic blocks per symbol > perf diff: Link same basic blocks among different data files > perf diff: Print the basic block cycles diff > perf diff: Documentation -c cycles option > > tools/perf/Documentation/perf-diff.txt | 14 +- > tools/perf/builtin-diff.c | 373 ++++++++++++++++++++++++++++++++- > tools/perf/ui/stdio/hist.c | 26 +++ > tools/perf/util/hist.c | 42 +++- > tools/perf/util/hist.h | 9 + > tools/perf/util/sort.h | 8 + > tools/perf/util/symbol.c | 22 ++ > tools/perf/util/symbol.h | 23 ++ > 8 files changed, 509 insertions(+), 8 deletions(-) > > -- > 2.7.4 >
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