Re: [PATCH v2 02/12] perf test: Truncate test description to fit terminal width

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

On Mon, Jun 15, 2026 at 11:13:54PM -0700, Ian Rogers wrote:
> The parallel test harness uses the carriage return delete escape sequence
> `PERF_COLOR_DELETE_LINE` ("\033[A\33[2K\r") to erase and update the
> "Running (X active)" progress lines.
> 
> However, if a test description is longer than the terminal width, the line
> wraps around. When this happens, the cursor up escape sequence `\033[A` only
> moves the cursor to the last wrapped row, leaving the top half of the description
> printed on the previous line. This leads to name duplication and output corruption
> spilling over multiple rows on consoles narrower than the maximum description length
> (e.g., 101 columns wide).
> 
> Fix this by dynamically querying the terminal width using `get_term_dimensions`
> and truncating the printed test descriptions using the `%-*.*s` printf format.
> We reserve 35 characters for prefix, status, and spacing metrics to guarantee
> the progress line never wraps.
> 
> Fixes: 0e036dcad4e6 ("perf test: Display number of active running tests")
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/tests/builtin-test.c | 110 ++++++++++++++++++++++++--------
>  1 file changed, 85 insertions(+), 25 deletions(-)
> 
> diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
> index afc06cec4954..65a2dc50ef55 100644
> --- a/tools/perf/tests/builtin-test.c
> +++ b/tools/perf/tests/builtin-test.c
> @@ -10,35 +10,39 @@
>  #ifdef HAVE_BACKTRACE_SUPPORT
>  #include <execinfo.h>
>  #endif
> -#include <poll.h>
> -#include <unistd.h>
>  #include <setjmp.h>
> -#include <string.h>
>  #include <stdlib.h>
> -#include <sys/types.h>
> +#include <string.h>
> +
>  #include <dirent.h>
> -#include <sys/wait.h>
> +#include <linux/kernel.h>
> +#include <linux/string.h>
> +#include <linux/zalloc.h>
> +#include <poll.h>
> +#include <sys/ioctl.h>
>  #include <sys/stat.h>
>  #include <sys/time.h>
> +#include <sys/types.h>
> +#include <sys/wait.h>
> +#include <unistd.h>
> +
> +#include <subcmd/exec-cmd.h>
> +#include <subcmd/parse-options.h>
> +#include <subcmd/run-command.h>
> +
>  #include "builtin.h"
> +#include "color.h"
>  #include "config.h"
> +#include "debug.h"
>  #include "hist.h"
>  #include "intlist.h"
> -#include "tests.h"
> -#include "debug.h"
> -#include "color.h"
> -#include <subcmd/parse-options.h>
> -#include <subcmd/run-command.h>
>  #include "string2.h"
>  #include "symbol.h"
> +#include "tests-scripts.h"
> +#include "tests.h"
>  #include "util/rlimit.h"
>  #include "util/strbuf.h"
> -#include <linux/kernel.h>
> -#include <linux/string.h>
> -#include <subcmd/exec-cmd.h>
> -#include <linux/zalloc.h>
> -
> -#include "tests-scripts.h"
> +#include "util/term.h"
>  
>  static const char *junit_filename;
>  static struct strbuf junit_xml_buf = STRBUF_INIT;
> @@ -413,19 +417,64 @@ static char *xml_escape(const char *str)
>  	return res ? res : strdup("");
>  }
>  
> +static int get_term_width(void)
> +{
> +	struct winsize ws;
> +	int cols = 80;
> +	int term_width;
> +

A comment here to explain this 10000 magic number?

> +	if (!isatty(1))
> +		return 10000;
> +
> +	get_term_dimensions(&ws);
> +	if (ws.ws_col > 0)
> +		cols = ws.ws_col;
> +
> +	/*
> +	 * Limit description width to fit on a single line. We subtract 35
> +	 * columns of headroom to allocate space for:
> +	 * - The suite index prefix: e.g. " 10.100:" (9 characters).
> +	 * - The colon separator and spaces: " : " (3 characters).
> +	 * - The longest status results: e.g. "Skip (some metrics failed)" (26 characters)
> +	 *   or "Running (XX active)" (20 characters).
> +	 *
> +	 * A minimum description width of 10 is enforced to ensure names are
> +	 * legible even on very narrow consoles.
> +	 */

> +	term_width = cols - 35;
> +	if (term_width < 10)
> +		term_width = 10;
> +
> +	return term_width;
> +}
> +
> +static int get_max_desc_width(int width)
> +{
> +	int term_width = get_term_width();
> +
> +	return width > term_width ? term_width : width;
> +}
> +
>  static int print_test_result(struct test_suite *t, int curr_suite, int curr_test_case,
>  			     int result, int width, int running,
>  			     const char *err_output, double elapsed)
>  {
> +	int pad_width = get_max_desc_width(width);
> +	int term_width = get_term_width();
> +
>  	if (test_suite__num_test_cases(t) > 1) {
>  		char prefix[32];
>  		int len = snprintf(prefix, sizeof(prefix), "%3d.%1d:",
>  				   curr_suite + 1, curr_test_case + 1);
> -		int subw = len >= 4 ? width + 4 - len : width;
> +		int pad = len >= 4 ? pad_width + 4 - len : pad_width;
> +		int trunc = len >= 4 ? term_width + 4 - len : term_width;
>  
> -		pr_info("%s %-*s:", prefix, subw, test_description(t, curr_test_case));
> -	} else
> -		pr_info("%3d: %-*s:", curr_suite + 1, width, test_description(t, curr_test_case));
> +		pr_info("%s %-*.*s:", prefix, pad, trunc,
> +			test_description(t, curr_test_case));
> +	} else {
> +		pr_info("%3d: %-*.*s:", curr_suite + 1, pad_width, term_width,
> +			test_description(t, curr_test_case));
> +	}
>  
>  	switch (result) {
>  	case TEST_RUNNING:
> @@ -695,6 +744,7 @@ static void finish_test(struct child_test **child_tests, int running_test, int c
>  	int ret;
>  	struct timespec end_time;
>  	double elapsed;
> +	width = get_max_desc_width(width);
>  
>  	if (child_test == NULL) {
>  		/* Test wasn't started. */
> @@ -709,7 +759,8 @@ static void finish_test(struct child_test **child_tests, int running_test, int c
>  	 * sub test names.
>  	 */
>  	if (test_suite__num_test_cases(t) > 1 && curr_test_case == 0)
> -		pr_info("%3d: %-*s:\n", curr_suite + 1, width, test_description(t, -1));
> +		pr_info("%3d: %-*.*s:\n", curr_suite + 1, width, width,
> +			test_description(t, -1));
>  
>  	/*
>  	 * Busy loop reading from the child's stdout/stderr that are set to be
> @@ -917,6 +968,8 @@ static int finish_tests_parallel(struct child_test **child_tests, size_t num_tes
>  	int last_suite_printed = -1;
>  	sigset_t set, oldset;
>  
> +	width = get_max_desc_width(width);
> +
>  	sigemptyset(&set);
>  	sigaddset(&set, SIGINT);
>  	sigaddset(&set, SIGTERM);
> @@ -985,8 +1038,11 @@ static int finish_tests_parallel(struct child_test **child_tests, size_t num_tes
>  			if (next_child) {
>  				if (test_suite__num_test_cases(next_child->test) > 1 &&
>  				    last_suite_printed != next_child->suite_num) {
> -					pr_info("%3d: %-*s:\n", next_child->suite_num + 1, width,
> -						test_description(next_child->test, -1));
> +					pr_info("%3d: %-*.*s:\n",
> +						next_child->suite_num + 1,
> +						width, width,
> +						test_description(
> +							next_child->test, -1));
>  					last_suite_printed = next_child->suite_num;
>  				}
>  				print_test_result(next_child->test, next_child->suite_num,
> @@ -1049,7 +1105,8 @@ static int finish_tests_parallel(struct child_test **child_tests, size_t num_tes
>  
>  			if (test_suite__num_test_cases(child->test) > 1 &&
>  			    last_suite_printed != child->suite_num) {
> -				pr_info("%3d: %-*s:\n", child->suite_num + 1, width,
> +				pr_info("%3d: %-*.*s:\n", child->suite_num + 1,
> +					width, width,
>  					test_description(child->test, -1));
>  				last_suite_printed = child->suite_num;
>  			}
> @@ -1296,7 +1353,10 @@ static int __cmd_test(struct test_suite **suites, int argc, const char *argv[],
>  
>  			if (intlist__find(skiplist, curr_suite + 1)) {
>  				if (pass == 1) {
> -					pr_info("%3d: %-*s:", curr_suite + 1, width,
> +					int pad_width = get_max_desc_width(width);
> +					int term_width = get_term_width();
> +
> +					pr_info("%3d: %-*.*s:", curr_suite + 1, pad_width, term_width,
>  						test_description(*t, -1));
>  					color_fprintf(stderr, PERF_COLOR_YELLOW,
>  						      " Skip (user override)\n");
> -- 
> 2.54.0.1136.gdb2ca164c4-goog