Re: [PATCH v9 2/2] perf test: Truncate printed test descriptions dynamically to avoid terminal wrapping

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Thu, Jun 04, 2026 at 09:36:27AM -0700, Ian Rogers wrote:
> When test descriptions are extremely long (e.g., the truncated perf.data
> graceful handling test is 103 characters long), they wrap across terminal
> boundaries.
> 
> Because the ANSI escape code to delete the line (PERF_COLOR_DELETE_LINE)
> only clears a single terminal line, visual wrapping leaves orphan
> wrapped lines on the screen, which results in the test description being
> printed multiple times.

  CC      /tmp/build/perf-tools-next/util/bpf_lock_contention.o
tests/builtin-test.c: In function ‘print_test_result.isra’:
tests/builtin-test.c:427:40: error: ‘%-*s’ directive output may be truncated writing between 20 and 65507 bytes into a region of size 256 [-Werror=format-truncation=]
  427 |                 snprintf(buf, buf_sz, "%-*s", width, desc);
      |                                        ^~~~
In file included from /usr/include/stdio.h:974,
                 from /home/acme/git/perf-tools-next/tools/include/linux/panic.h:6,
                 from /home/acme/git/perf-tools-next/tools/include/linux/kernel.h:11,
                 from /home/acme/git/perf-tools-next/tools/include/linux/list.h:7,
                 from /home/acme/git/perf-tools-next/tools/perf/util/config.h:6,
                 from tests/builtin-test.c:26:
In function ‘snprintf’,
    inlined from ‘format_test_description’ at tests/builtin-test.c:427:3,
    inlined from ‘print_test_result.isra’ at tests/builtin-test.c:473:3:
/usr/include/bits/stdio2.h:68:10: note: ‘__builtin___snprintf_chk’ output between 21 and 65508 bytes into a destination of size 256
   68 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   69 |                                    __glibc_objsize (__s), __fmt,
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   70 |                                    __va_arg_pack ());
      |                                    ~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[4]: *** [/home/acme/git/perf-tools-next/tools/build/Makefile.build:95: /tmp/build/perf-tools-next/tests/builtin-test.o] Error 1
make[3]: *** [/home/acme/git/perf-tools-next/tools/build/Makefile.build:158: tests] Error 2
make[2]: *** [Makefile.perf:566: /tmp/build/perf-tools-next/perf-test-in.o] Error 2
make[2]: *** Waiting for unfinished jobs....
  LD      /tmp/build/perf-tools-next/util/perf-util-in.o
  LD      /tmp/build/perf-tools-next/perf-util-in.o
make[1]: *** [Makefile.perf:288: sub-make] Error 2
make: *** [Makefile:122: install-bin] Error 2
make: Leaving directory '/home/acme/git/perf-tools-next/tools/perf'
⬢ [acme@toolbx perf-tools-next]$


I thought you had fixed this one?

The first patch is applied, testing with it now.

- Arnaldo