On Fri, Jun 28, 2019 at 05:22:57PM +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. > > With this patch set, for example, > > $ perf record -b ./div > $ perf record -b ./div > $ perf diff -c cycles > > # Event 'cycles' > # > # Baseline [Program Block Range] > Cycles Diff Shared Object Symbol > # ........ > ...................................................................... > ................ .................................. > # > 48.75% [div.c:42 -> > div.c:45] 147 div [.] main > 48.75% [div.c:31 -> > div.c:40] 4 div [.] main > 48.75% [div.c:40 -> > div.c:40] 0 div [.] main > 48.75% [div.c:42 -> > div.c:42] 0 div [.] main > 48.75% [div.c:42 -> > div.c:44] 0 div [.] main > 19.02% [random_r.c:357 -> > random_r.c:360] 0 libc-2.23.so [.] __random_r > 19.02% [random_r.c:357 -> > random_r.c:373] 0 libc-2.23.so [.] __random_r > 19.02% [random_r.c:357 -> > random_r.c:376] 0 libc-2.23.so [.] __random_r > 19.02% [random_r.c:357 -> > random_r.c:380] 0 libc-2.23.so [.] __random_r > 19.02% [random_r.c:357 -> > random_r.c:392] 0 libc-2.23.so [.] __random_r > 16.17% [random.c:288 -> > random.c:291] 0 libc-2.23.so [.] __random > 16.17% [random.c:288 -> > random.c:291] 0 libc-2.23.so [.] __random > 16.17% [random.c:288 -> > random.c:295] 0 libc-2.23.so [.] __random > 16.17% [random.c:288 -> > random.c:297] 0 libc-2.23.so [.] __random > 16.17% [random.c:291 -> > random.c:291] 0 libc-2.23.so [.] __random > 16.17% [random.c:293 -> > random.c:293] 0 libc-2.23.so [.] __random > 8.21% [div.c:22 -> > div.c:22] 148 div [.] compute_flag > 8.21% [div.c:22 -> > div.c:25] 0 div [.] compute_flag > 8.21% [div.c:27 -> > div.c:28] 0 div [.] compute_flag > 5.52% [rand.c:26 -> > rand.c:27] 0 libc-2.23.so [.] rand > 5.52% [rand.c:26 -> > rand.c:28] 0 libc-2.23.so [.] rand > 2.27% [rand@plt+0 -> > rand@plt+0] 0 div [.] rand@plt > 0.01% [entry_64.S:694 -> > entry_64.S:694] 16 [kernel.vmlinux] [k] native_irq_return_iret > 0.00% [fair.c:7676 -> > fair.c:7665] 162 [kernel.vmlinux] [k] update_blocked_averages > > '[Program Block Range]' indicates the range of program basic block > (start -> end). If we can find the source line it prints the source > line otherwise it prints the symbol+offset instead. > > v6: > --- > Remove the 'ops' argument in hists__add_entry_block. No functional change. > > Changed patches > perf util: Add block_info in hist_entry > perf diff: Use hists to manage basic blocks per symbol
Reviewed-by: Jiri Olsa <[email protected]> thanks, jirka
