rtla/timerlat: Make user-space threads the default

After ther -u addition, most of the known users are setting it. And
it makes sense, as it adds more information, and inherits the default
setup for the threads - e.g., cgroups configs.

Thus, if the user-space interface is available, enable -u. Otherwise,
use the in-kernel thread.

Add the -k option to allow the user to request kernel-threads.

Link: https://lkml.kernel.org/r/9241d3089de4091b124f780ed832a0e6646cadaa.1713968967.git.bristot@kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>

diff --git a/Documentation/tools/rtla/common_timerlat_options.rst b/Documentation/tools/rtla/common_timerlat_options.rst
index d3255ed70195faafe9c9affaef7e751e3049b002..090700a6ae9f0f1c1a12a27e8539b3059c3b7267 100644 (file)
--- a/Documentation/tools/rtla/common_timerlat_options.rst
+++ b/Documentation/tools/rtla/common_timerlat_options.rst
@@ -27,12 +27,16 @@
         *cyclictest* sets this value to *0* by default, use **--dma-latency** *0* to have
         similar results.
 
+**-k**, **--kernel-threads**
+
+        Use timerlat kernel-space threads, in contrast of **-u**.
+
 **-u**, **--user-threads**
 
         Set timerlat to run without a workload, and then dispatches user-space workloads
         to wait on the timerlat_fd. Once the workload is awakes, it goes to sleep again
         adding so the measurement for the kernel-to-user and user-to-kernel to the tracer
-        output.
+        output. **--user-threads** will be used unless the user specify **-k**.
 
 **-U**, **--user-load**
 

diff --git a/tools/tracing/rtla/src/timerlat_hist.c b/tools/tracing/rtla/src/timerlat_hist.c
index da1c353bdac9d67c40e7bc78c4e71856557e33da..6eb6e38d4a05beac59a963c85c87d666355dd7db 100644 (file)
--- a/tools/tracing/rtla/src/timerlat_hist.c
+++ b/tools/tracing/rtla/src/timerlat_hist.c
@@ -40,6 +40,7 @@ struct timerlat_hist_params {
        int                     no_aa;
        int                     dump_tasks;
        int                     user_workload;
+       int                     kernel_workload;
        int                     user_hist;
        cpu_set_t               hk_cpu_set;
        struct sched_attr       sched_param;
@@ -628,7 +629,7 @@ static void timerlat_hist_usage(char *usage)
                "  usage: [rtla] timerlat hist [-h] [-q] [-d s] [-D] [-n] [-a us] [-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] [-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]",
+               "         [--no-index] [--with-zeros] [--dma-latency us] [-C[=cgroup_name]] [--no-aa] [--dump-task] [-u|-k]",
                "         [--warm-up s]",
                "",
                "         -h/--help: print this menu",
@@ -664,7 +665,8 @@ static void timerlat_hist_usage(char *usage)
                "               f:prio - use SCHED_FIFO with prio",
                "               d:runtime[us|ms|s]:period[us|ms|s] - use SCHED_DEADLINE with runtime and period",
                "                                                      in nanoseconds",
-               "         -u/--user-threads: use rtla user-space threads instead of in-kernel timerlat threads",
+               "         -u/--user-threads: use rtla user-space threads instead of kernel-space timerlat threads",
+               "         -k/--kernel-threads: use timerlat kernel-space threads instead of rtla user-space threads",
                "         -U/--user-load: enable timerlat for user-defined user-space workload",
                "            --warm-up s: let the workload run for s seconds before collecting data",
                NULL,
@@ -728,6 +730,7 @@ static struct timerlat_hist_params
                        {"thread",              required_argument,      0, 'T'},
                        {"trace",               optional_argument,      0, 't'},
                        {"user-threads",        no_argument,            0, 'u'},
+                       {"kernel-threads",      no_argument,            0, 'k'},
                        {"user-load",           no_argument,            0, 'U'},
                        {"event",               required_argument,      0, 'e'},
                        {"no-irq",              no_argument,            0, '0'},
@@ -748,7 +751,7 @@ static struct timerlat_hist_params
                /* getopt_long stores the option index here. */
                int option_index = 0;
 
-               c = getopt_long(argc, argv, "a:c:C::b:d:e:E:DhH:i:np:P:s:t::T:uU0123456:7:8:9\1\2:",
+               c = getopt_long(argc, argv, "a:c:C::b:d:e:E:DhH:i:knp:P:s:t::T:uU0123456:7:8:9\1\2:",
                                 long_options, &option_index);
 
                /* detect the end of the options. */
@@ -831,6 +834,9 @@ static struct timerlat_hist_params
                case 'i':
                        params->stop_us = get_llong_from_str(optarg);
                        break;
+               case 'k':
+                       params->kernel_workload = 1;
+                       break;
                case 'n':
                        params->output_divisor = 1;
                        break;
@@ -942,6 +948,9 @@ static struct timerlat_hist_params
        if (!params->stop_us && !params->stop_total_us)
                params->no_aa = 1;
 
+       if (params->kernel_workload && params->user_workload)
+               timerlat_hist_usage("--kernel-threads and --user-threads are mutually exclusive!");
+
        return params;
 }
 
@@ -1017,6 +1026,22 @@ timerlat_hist_apply_config(struct osnoise_tool *tool, struct timerlat_hist_param
                auto_house_keeping(&params->monitored_cpus);
        }
 
+       /*
+        * If the user did not specify a type of thread, try user-threads first.
+        * Fall back to kernel threads otherwise.
+        */
+       if (!params->kernel_workload && !params->user_workload) {
+               retval = tracefs_file_exists(NULL, "osnoise/per_cpu/cpu0/timerlat_fd");
+               if (retval) {
+                       debug_msg("User-space interface detected, setting user-threads\n");
+                       params->user_workload = 1;
+                       params->user_hist = 1;
+               } else {
+                       debug_msg("User-space interface not detected, setting kernel-threads\n");
+                       params->kernel_workload = 1;
+               }
+       }
+
        if (params->user_hist) {
                retval = osnoise_set_workload(tool->context, 0);
                if (retval) {

diff --git a/tools/tracing/rtla/src/timerlat_top.c b/tools/tracing/rtla/src/timerlat_top.c
index 410eb51749132b2ed1d303b9b512057cc6554bab..0acfefe151f752f5bd61d22c8b4b8836773b5060 100644 (file)
--- a/tools/tracing/rtla/src/timerlat_top.c
+++ b/tools/tracing/rtla/src/timerlat_top.c
@@ -44,6 +44,7 @@ struct timerlat_top_params {
        int                     hk_cpus;
        int                     user_top;
        int                     user_workload;
+       int                     kernel_workload;
        int                     pretty_output;
        int                     warmup;
        cpu_set_t               hk_cpu_set;
@@ -445,7 +446,7 @@ 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] [--warm-up s]",
+               "         [-P priority] [--dma-latency us] [--aa-only us] [-C[=cgroup_name]] [-u|-k] [--warm-up s]",
                "",
                "         -h/--help: print this menu",
                "         -a/--auto: set automatic trace mode, stopping the session if argument in us latency is hit",
@@ -474,7 +475,8 @@ static void timerlat_top_usage(char *usage)
                "               f:prio - use SCHED_FIFO with prio",
                "               d:runtime[us|ms|s]:period[us|ms|s] - use SCHED_DEADLINE with runtime and period",
                "                                                      in nanoseconds",
-               "         -u/--user-threads: use rtla user-space threads instead of in-kernel timerlat threads",
+               "         -u/--user-threads: use rtla user-space threads instead of kernel-space timerlat threads",
+               "         -k/--kernel-threads: use timerlat kernel-space threads instead of rtla user-space threads",
                "         -U/--user-load: enable timerlat for user-defined user-space workload",
                "            --warm-up s: let the workload run for s seconds before collecting data",
                NULL,
@@ -536,6 +538,7 @@ static struct timerlat_top_params
                        {"thread",              required_argument,      0, 'T'},
                        {"trace",               optional_argument,      0, 't'},
                        {"user-threads",        no_argument,            0, 'u'},
+                       {"kernel-threads",      no_argument,            0, 'k'},
                        {"user-load",           no_argument,            0, 'U'},
                        {"trigger",             required_argument,      0, '0'},
                        {"filter",              required_argument,      0, '1'},
@@ -550,7 +553,7 @@ static struct timerlat_top_params
                /* getopt_long stores the option index here. */
                int option_index = 0;
 
-               c = getopt_long(argc, argv, "a:c:C::d:De:hH:i:np:P:qs:t::T:uU0:1:2:345:6:",
+               c = getopt_long(argc, argv, "a:c:C::d:De:hH:i:knp:P:qs:t::T:uU0:1:2:345:6:",
                                 long_options, &option_index);
 
                /* detect the end of the options. */
@@ -635,6 +638,9 @@ static struct timerlat_top_params
                case 'i':
                        params->stop_us = get_llong_from_str(optarg);
                        break;
+               case 'k':
+                       params->kernel_workload = true;
+                       break;
                case 'n':
                        params->output_divisor = 1;
                        break;
@@ -729,6 +735,9 @@ static struct timerlat_top_params
        if (params->no_aa && params->aa_only)
                timerlat_top_usage("--no-aa and --aa-only are mutually exclusive!");
 
+       if (params->kernel_workload && params->user_workload)
+               timerlat_top_usage("--kernel-threads and --user-threads are mutually exclusive!");
+
        return params;
 }
 
@@ -807,6 +816,22 @@ timerlat_top_apply_config(struct osnoise_tool *top, struct timerlat_top_params *
                auto_house_keeping(&params->monitored_cpus);
        }
 
+       /*
+        * If the user did not specify a type of thread, try user-threads first.
+        * Fall back to kernel threads otherwise.
+        */
+       if (!params->kernel_workload && !params->user_workload) {
+               retval = tracefs_file_exists(NULL, "osnoise/per_cpu/cpu0/timerlat_fd");
+               if (retval) {
+                       debug_msg("User-space interface detected, setting user-threads\n");
+                       params->user_workload = 1;
+                       params->user_top = 1;
+               } else {
+                       debug_msg("User-space interface not detected, setting kernel-threads\n");
+                       params->kernel_workload = 1;
+               }
+       }
+
        if (params->user_top) {
                retval = osnoise_set_workload(top->context, 0);
                if (retval) {