linux-kernel - [PATCH v2 2/2] perf help: Lower levenshtein penality for deleting character

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Date: Fri,  1 Mar 2024 12:13:06 -0800
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/2] perf help: Lower levenshtein penality for deleting character

The levenshtein penalty for deleting a character was far higher than
subsituting or inserting a character. Lower the penalty to match that
of inserting a character.

Before:
```
$ perf recccord
perf: 'recccord' is not a perf-command. See 'perf --help'.
```

After:
```
$ perf recccord
perf: 'recccord' is not a perf-command. See 'perf --help'.

Did you mean this?
        record
```

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/help-unknown-cmd.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/help-unknown-cmd.c b/tools/perf/util/help-unknown-cmd.c
index 2ba3369f1620..a0a46e34f8d1 100644
--- a/tools/perf/util/help-unknown-cmd.c
+++ b/tools/perf/util/help-unknown-cmd.c
@@ -73,10 +73,14 @@ const char *help_unknown_cmd(const char *cmd, struct cmdnames *main_cmds)
 
 	if (main_cmds->cnt) {
 		/* This reuses cmdname->len for similarity index */
-		for (i = 0; i < main_cmds->cnt; ++i)
+		for (i = 0; i < main_cmds->cnt; ++i) {
 			main_cmds->names[i]->len =
-				levenshtein(cmd, main_cmds->names[i]->name, 0, 2, 1, 4);
-
+				levenshtein(cmd, main_cmds->names[i]->name,
+					/*swap_penalty=*/0,
+					/*substition_penality=*/2,
+					/*insertion_penality=*/1,
+					/*deletion_penalty=*/1);
+		}
 		qsort(main_cmds->names, main_cmds->cnt,
 		      sizeof(*main_cmds->names), levenshtein_compare);
 
-- 
2.44.0.278.ge034bb2e1d-goog