linux-kernel - [PATCH 4/5] rtla/timerlat: Add --disable-idle-states for hist

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Message-ID: <20240612145439.206990-5-tglozar@redhat.com>
Date: Wed, 12 Jun 2024 16:54:38 +0200
From: tglozar@...hat.com
To: bristot@...nel.org,
	rostedt@...dmis.org
Cc: linux-trace-kernel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	jkacur@...hat.com,
	jwyatt@...hat.com,
	Tomas Glozar <tglozar@...hat.com>
Subject: [PATCH 4/5] rtla/timerlat: Add --disable-idle-states for hist

From: Tomas Glozar <tglozar@...hat.com>

Support disabling idle states also for timerlat-hist.

Signed-off-by: Tomas Glozar <tglozar@...hat.com>
---
 tools/tracing/rtla/src/timerlat_hist.c | 35 +++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/tools/tracing/rtla/src/timerlat_hist.c b/tools/tracing/rtla/src/timerlat_hist.c
index a3907c390d67..69d427841d14 100644
--- a/tools/tracing/rtla/src/timerlat_hist.c
+++ b/tools/tracing/rtla/src/timerlat_hist.c
@@ -55,6 +55,7 @@ struct timerlat_hist_params {
 	int			entries;
 	int			warmup;
 	int			buffer_size;
+	int			disable_idle_states;
 };
 
 struct timerlat_hist_cpu {
@@ -655,7 +656,7 @@ static void timerlat_hist_usage(char *usage)
 		"         [-t[file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] [-c cpu-list] [-H cpu-list]\\",
 		"	  [-P priority] [-E N] [-b N] [--no-irq] [--no-thread] [--no-header] [--no-summary] \\",
 		"	  [--no-index] [--with-zeros] [--dma-latency us] [-C[=cgroup_name]] [--no-aa] [--dump-task] [-u|-k]",
-		"	  [--warm-up s]",
+		"	  [--warm-up s] [--disable-idle-states]",
 		"",
 		"	  -h/--help: print this menu",
 		"	  -a/--auto: set automatic trace mode, stopping the session if argument in us latency is hit",
@@ -695,6 +696,7 @@ static void timerlat_hist_usage(char *usage)
 		"	  -U/--user-load: enable timerlat for user-defined user-space workload",
 		"	     --warm-up s: let the workload run for s seconds before collecting data",
 		"	     --trace-buffer-size kB: set the per-cpu trace buffer size in kB",
+		"	     --disable-idle-states: disable all idle states for cpus used by timerlat to reduce exit from idle latency",
 		NULL,
 	};
 
@@ -732,6 +734,9 @@ static struct timerlat_hist_params
 	/* disabled by default */
 	params->dma_latency = -1;
 
+	/* disabled by default */
+	params->disable_idle_states = 0;
+
 	/* display data in microseconds */
 	params->output_divisor = 1000;
 	params->bucket_size = 1;
@@ -772,6 +777,7 @@ static struct timerlat_hist_params
 			{"dump-task",		no_argument,		0, '\1'},
 			{"warm-up",		required_argument,	0, '\2'},
 			{"trace-buffer-size",	required_argument,	0, '\3'},
+			{"disable-idle-states",	no_argument,		0, '\4'},
 			{0, 0, 0, 0}
 		};
 
@@ -960,6 +966,9 @@ static struct timerlat_hist_params
 		case '\3':
 			params->buffer_size = get_llong_from_str(optarg);
 			break;
+		case '\4':
+			params->disable_idle_states = 1;
+			break;
 		default:
 			timerlat_hist_usage("Invalid option");
 		}
@@ -1152,6 +1161,7 @@ int timerlat_hist_main(int argc, char *argv[])
 	int return_value = 1;
 	pthread_t timerlat_u;
 	int retval;
+	int i;
 
 	params = timerlat_hist_parse_args(argc, argv);
 	if (!params)
@@ -1201,6 +1211,21 @@ int timerlat_hist_main(int argc, char *argv[])
 		}
 	}
 
+	if (params->disable_idle_states) {
+		for (i = 0; i < sysconf(_SC_NPROCESSORS_CONF); i++) {
+			if (params->cpus && !CPU_ISSET(i, &params->monitored_cpus))
+				continue;
+			if (save_cpu_idle_disable_state(i) < 0) {
+				err_msg("Could not save cpu idle state.\n");
+				goto out_free;
+			}
+			if (set_cpu_idle_disable_state(i, 1) < 0) {
+				err_msg("Could not disable cpu idle state.\n");
+				goto out_free;
+			}
+		}
+	}
+
 	if (params->trace_output) {
 		record = osnoise_init_trace_tool("timerlat");
 		if (!record) {
@@ -1332,6 +1357,13 @@ int timerlat_hist_main(int argc, char *argv[])
 	timerlat_aa_destroy();
 	if (dma_latency_fd >= 0)
 		close(dma_latency_fd);
+	if (params->disable_idle_states) {
+		for (i = 0; i < sysconf(_SC_NPROCESSORS_CONF); i++) {
+			if (params->cpus && !CPU_ISSET(i, &params->monitored_cpus))
+				continue;
+			restore_cpu_idle_disable_state(i);
+		}
+	}
 	trace_events_destroy(&record->trace, params->events);
 	params->events = NULL;
 out_free:
@@ -1340,6 +1372,7 @@ int timerlat_hist_main(int argc, char *argv[])
 	osnoise_destroy_tool(record);
 	osnoise_destroy_tool(tool);
 	free(params);
+	free_cpu_idle_disable_states();
 out_exit:
 	exit(return_value);
 }
-- 
2.43.0