Re: [PATCH v3 0/3] perf report/annotate: Support average IPC and IPC coverage for function

Ingo Molnar
2018-11-28T09:10:12Z

* Jin Yao <yao.jin@linux.intel.com> wrote:

> Add supporting of displaying the average IPC and IPC coverage
> percentage per function.
>
> For example,
>
> $ perf record -b ...
> $ perf report -s symbol or
> perf report -s symbol --stdio
>
> Overhead Symbol IPC [IPC Coverage]
> 39.60% [.] __random 2.30 [ 54.8%]
> 18.02% [.] main 0.43 [ 54.3%]
> 14.21% [.] compute_flag 2.29 [100.0%]
> 14.16% [.] rand 0.36 [100.0%]
> 7.06% [.] __random_r 2.57 [ 70.5%]
> 6.85% [.] rand@plt 0.00 [ 0.0%]
> ...
>
> $ perf annotate --stdio2
>
> Percent IPC Cycle (Average IPC: 2.30, IPC Coverage: 54.8%)
>
> Disassembly of section .text:
>
> 000000000003aac0 <random@@GLIBC_2.2.5>:
> 8.32 3.28 sub $0x18,%rsp
> 3.28 mov $0x1,%esi
> 3.28 xor %eax,%eax
> 3.28 cmpl $0x0,argp_program_version_hook@@GLIBC_2.2.5+0x1e0
> 11.57 3.28 1 ↓ je 20
> lock cmpxchg %esi,__abort_msg@@GLIBC_PRIVATE+0x8a0
> ↓ jne 29
> ↓ jmp 43
> 11.57 1.10 20: cmpxchg %esi,__abort_msg@@GLIBC_PRIVATE+0x8a0

That's a nice feature: please add meaningful documentation, accessible
via the perf help system preferably, that outlines how the IPC metrics
should be interpreted and how they are useful when optimizing programs.

Thanks,

Ingo