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SubjectRe: [PATCH v6 0/7] perf diff: diff cycles at basic block level
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 <jolsa@kernel.org>

thanks,
jirka

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