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

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Date:   Tue, 23 Jul 2019 14:47:47 -0700
From:   tip-bot for Andi Kleen <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mingo@...nel.org, tglx@...utronix.de, linux-kernel@...r.kernel.org,
        acme@...hat.com, hpa@...or.com, jolsa@...nel.org,
        denis.bakhvalov@...el.com, ak@...ux.intel.com
Subject: [tip:perf/urgent] perf script: Fix off by one in brstackinsn IPC
 computation

Commit-ID:  dde4e732a5b02fa5599c2c0e6c48a0c11789afc4
Gitweb:     https://git.kernel.org/tip/dde4e732a5b02fa5599c2c0e6c48a0c11789afc4
Author:     Andi Kleen <ak@...ux.intel.com>
AuthorDate: Thu, 11 Jul 2019 11:19:21 -0700
Committer:  Arnaldo Carvalho de Melo <acme@...hat.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@...el.com>
Signed-off-by: Andi Kleen <ak@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Link: http://lkml.kernel.org/r/20190711181922.18765-2-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.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);