rtla/timerlat: Add --deepest-idle-state for top

Add option to limit deepest idle state on CPUs where timerlat is running
for the duration of the workload.

Link: https://lore.kernel.org/20241017140914.3200454-5-tglozar@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/tools/tracing/rtla/src/timerlat_top.c b/tools/tracing/rtla/src/timerlat_top.c
index 7fb85c8ee3bce1394146f9799a4f9dae03976aba..fca0da3caa876aefaf2920b32ed7bff19448aafd 100644 (file)
--- a/tools/tracing/rtla/src/timerlat_top.c
+++ b/tools/tracing/rtla/src/timerlat_top.c
@@ -48,6 +48,7 @@ struct timerlat_top_params {
        int                     pretty_output;
        int                     warmup;
        int                     buffer_size;
+       int                     deepest_idle_state;
        cpu_set_t               hk_cpu_set;
        struct sched_attr       sched_param;
        struct trace_events     *events;
@@ -447,7 +448,7 @@ static void timerlat_top_usage(char *usage)
                "",
                "  usage: rtla timerlat [top] [-h] [-q] [-a us] [-d s] [-D] [-n] [-p us] [-i us] [-T us] [-s us] \\",
                "         [[-t[file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] [-c cpu-list] [-H cpu-list]\\",
-               "         [-P priority] [--dma-latency us] [--aa-only us] [-C[=cgroup_name]] [-u|-k] [--warm-up s]",
+               "         [-P priority] [--dma-latency us] [--aa-only us] [-C[=cgroup_name]] [-u|-k] [--warm-up s] [--deepest-idle-state n]",
                "",
                "         -h/--help: print this menu",
                "         -a/--auto: set automatic trace mode, stopping the session if argument in us latency is hit",
@@ -481,6 +482,7 @@ static void timerlat_top_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",
+               "            --deepest-idle-state n: only go down to idle state n on cpus used by timerlat to reduce exit from idle latency",
                NULL,
        };
 
@@ -518,6 +520,9 @@ static struct timerlat_top_params
        /* disabled by default */
        params->dma_latency = -1;
 
+       /* disabled by default */
+       params->deepest_idle_state = -2;
+
        /* display data in microseconds */
        params->output_divisor = 1000;
 
@@ -550,6 +555,7 @@ static struct timerlat_top_params
                        {"aa-only",             required_argument,      0, '5'},
                        {"warm-up",             required_argument,      0, '6'},
                        {"trace-buffer-size",   required_argument,      0, '7'},
+                       {"deepest-idle-state",  required_argument,      0, '8'},
                        {0, 0, 0, 0}
                };
 
@@ -726,6 +732,9 @@ static struct timerlat_top_params
                case '7':
                        params->buffer_size = get_llong_from_str(optarg);
                        break;
+               case '8':
+                       params->deepest_idle_state = get_llong_from_str(optarg);
+                       break;
                default:
                        timerlat_top_usage("Invalid option");
                }
@@ -922,6 +931,7 @@ int timerlat_top_main(int argc, char *argv[])
        int return_value = 1;
        char *max_lat;
        int retval;
+       int nr_cpus, i;
 
        params = timerlat_top_parse_args(argc, argv);
        if (!params)
@@ -971,6 +981,28 @@ int timerlat_top_main(int argc, char *argv[])
                }
        }
 
+       if (params->deepest_idle_state >= -1) {
+               if (!have_libcpupower_support()) {
+                       err_msg("rtla built without libcpupower, --deepest-idle-state is not supported\n");
+                       goto out_free;
+               }
+
+               nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
+
+               for (i = 0; i < nr_cpus; 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_deepest_cpu_idle_state(i, params->deepest_idle_state) < 0) {
+                               err_msg("Could not set deepest cpu idle state.\n");
+                               goto out_free;
+                       }
+               }
+       }
+
        if (params->trace_output) {
                record = osnoise_init_trace_tool("timerlat");
                if (!record) {
@@ -1125,6 +1157,13 @@ out_top:
        timerlat_aa_destroy();
        if (dma_latency_fd >= 0)
                close(dma_latency_fd);
+       if (params->deepest_idle_state >= -1) {
+               for (i = 0; i < nr_cpus; 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:
@@ -1134,6 +1173,7 @@ out_free:
        osnoise_destroy_tool(record);
        osnoise_destroy_tool(top);
        free(params);
+       free_cpu_idle_disable_states();
 out_exit:
        exit(return_value);
 }