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rtla/timerlat: Make user-space threads the default
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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>
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Daniel Bristot de Oliveira committed May 15, 2024
1 parent cdbf719 commit fb9e90a
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Showing 3 changed files with 61 additions and 7 deletions.
6 changes: 5 additions & 1 deletion Documentation/tools/rtla/common_timerlat_options.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -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**

Expand Down
31 changes: 28 additions & 3 deletions tools/tracing/rtla/src/timerlat_hist.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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",
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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'},
Expand All @@ -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. */
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;
}

Expand Down Expand Up @@ -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) {
Expand Down
31 changes: 28 additions & 3 deletions tools/tracing/rtla/src/timerlat_top.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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",
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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'},
Expand All @@ -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. */
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;
}

Expand Down Expand Up @@ -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) {
Expand Down

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