[tip:perf/urgent] perf script: Fix off by one in brstackinsn IPC computation

tip-bot for Andi Kleen
2019-07-23T21:47:58Z

Commit-ID: dde4e732a5b02fa5599c2c0e6c48a0c11789afc4
Gitweb: https://git.kernel.org/tip/dde4e732a5b02fa5599c2c0e6c48a0c11789afc4
Author: Andi Kleen <ak@linux.intel.com>
AuthorDate: Thu, 11 Jul 2019 11:19:21 -0700
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 23 Jul 2019 08:59:37 -0300

perf script: Fix off by one in brstackinsn IPC computation

When we hit the end of a program block, need to count the last
instruction too for the IPC computation. This caused large errors for
small blocks.

% perf script -b ls / > /dev/null

Before:

% perf script -F +brstackinsn --xed
...
00007f94c9ac70d8 jz 0x7f94c9ac70e3 # PRED 3 cycles [36] 4.33 IPC
00007f94c9ac70e3 testb $0x20, 0x31d(%rbx)
00007f94c9ac70ea jnz 0x7f94c9ac70b0
00007f94c9ac70ec testb $0x8, 0x205ad(%rip)
00007f94c9ac70f3 jz 0x7f94c9ac6ff0 # PRED 1 cycles [37] 3.00 IPC

After:

% perf script -F +brstackinsn --xed
...
00007f94c9ac70d8 jz 0x7f94c9ac70e3 # PRED 3 cycles [15] 4.67 IPC
00007f94c9ac70e3 testb $0x20, 0x31d(%rbx)
00007f94c9ac70ea jnz 0x7f94c9ac70b0
00007f94c9ac70ec testb $0x8, 0x205ad(%rip)
00007f94c9ac70f3 jz 0x7f94c9ac6ff0 # PRED 1 cycles [16] 4.00 IPC

Suggested-by: Denis Bakhvalov <denis.bakhvalov@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20190711181922.18765-2-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-script.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 8f24865596af..0140ddb8dd0b 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -1059,7 +1059,7 @@ static int perf_sample__fprintf_brstackinsn(struct perf_sample *sample,

printed += ip__fprintf_sym(ip, thread, x.cpumode, x.cpu, &lastsym, attr, fp);
if (ip == end) {
- printed += ip__fprintf_jump(ip, &br->entries[i], &x, buffer + off, len - off, insn, fp,
+ printed += ip__fprintf_jump(ip, &br->entries[i], &x, buffer + off, len - off, ++insn, fp,
&total_cycles);
if (PRINT_FIELD(SRCCODE))
printed += print_srccode(thread, x.cpumode, ip);