[PATCH 3/5] rtla/timerlat: Add --disable-idle-states for top

[tglozar]

From: Tomas Glozar <tglo...@redhat.com>

Add option to disable idle states on CPUs where timerlat is running for
the duration of the workload.

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

diff --git a/tools/tracing/rtla/src/timerlat_top.c 
b/tools/tracing/rtla/src/timerlat_top.c
index 8c16419fe22a..dd1e5b03d781 100644
--- 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                     disable_idle_states;
        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] [--disable-idle-states]",
                "",
                "         -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",
+               "            --disable-idle-states: disable all idle states for 
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->disable_idle_states = 0;
+
        /* 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'},
+                       {"disable-idle-states", no_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->disable_idle_states = 1;
+                       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 i;
 
        params = timerlat_top_parse_args(argc, argv);
        if (!params)
@@ -971,6 +981,21 @@ int timerlat_top_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) {
@@ -1125,6 +1150,13 @@ int timerlat_top_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:
@@ -1134,6 +1166,7 @@ int timerlat_top_main(int argc, char *argv[])
        osnoise_destroy_tool(record);
        osnoise_destroy_tool(top);
        free(params);
+       free_cpu_idle_disable_states();
 out_exit:
        exit(return_value);
 }
-- 
2.43.0