On Wed, 31 Jul 2024 10:36:53 +0200
tglo...@redhat.com wrote:
> From: Tomas Glozar <tglo...@redhat.com>
>
> Add option to limit deepest idle state 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 | 46 ++++++++++++++++++++++++++-
> 1 file changed, 45 insertions(+), 1 deletion(-)
>
> diff --git a/tools/tracing/rtla/src/timerlat_top.c
> b/tools/tracing/rtla/src/timerlat_top.c
> index 8c16419fe22a..ef1d3affef95 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 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",
Could probably do:
#ifdef HAVE_LIBCPUPOWER_SUPPORT
> + " --deepest-idle-state n: only go down to idle state
> n on cpus used by timerlat to reduce exit from idle latency",
#else
+ " --deepest-idle-state n: [rtla built without
libcpupower, --deepest-idle-state is not supported]",
#endif
> 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 +931,9 @@ int timerlat_top_main(int argc, char *argv[])
> int return_value = 1;
> char *max_lat;
> int retval;
> +#ifdef HAVE_LIBCPUPOWER_SUPPORT
> + int i;
> +#endif /* HAVE_LIBCPUPOWER_SUPPORT */
>
> params = timerlat_top_parse_args(argc, argv);
> if (!params)
> @@ -971,6 +983,26 @@ int timerlat_top_main(int argc, char *argv[])
> }
> }
>
> + if (params->deepest_idle_state >= -1) {
> +#ifdef HAVE_LIBCPUPOWER_SUPPORT
> + for (i = 0; i < sysconf(_SC_NPROCESSORS_CONF); i++) {
> + if (params->cpus && !CPU_ISSET(i,
> ¶ms->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;
> + }
> + }
> +#else
> + err_msg("rtla built without libcpupower, --deepest-idle-state
> is not supported\n");
> + goto out_free;
> +#endif /* HAVE_LIBCPUPOWER_SUPPORT */
We could get rid of most of the ifdefs if you changed the header file to be:
#ifdef HAVE_LIBCPUPOWER_SUPPORT
int save_cpu_idle_disable_state(unsigned int cpu);
int restore_cpu_idle_disable_state(unsigned int cpu);
void free_cpu_idle_disable_states(void);
int set_deepest_cpu_idle_state(unsigned int cpu, unsigned int state);
static inline have_libcpower_support(void) { return 1; }
#else
static inline int save_cpu_idle_disable_state(unsigned int cpu) { return -1 }
static inline int restore_cpu_idle_disable_state(unsigned int cpu) { return -1;
}
static inline void free_cpu_idle_disable_states(void) { }
static inline int set_deepest_cpu_idle_state(unsigned int cpu, unsigned int
state) { return -1 }
static inline have_libcpower_support(void) { return 0; }
#endif /* HAVE_LIBCPUPOWER_SUPPORT */
Then the above can simply be:
if (params->deepest_idle_state >= -1) {
if (!have_libcpower_support()) {
err_msg("rtla built without libcpupower,
--deepest-idle-state is not supported\n");
goto out_free;
}
for (i = 0; i < sysconf(_SC_NPROCESSORS_CONF); i++) {
if (params->cpus && !CPU_ISSET(i,
¶ms->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;
}
}
Makes the code much nicer to look at.
> + }
> +
> if (params->trace_output) {
> record = osnoise_init_trace_tool("timerlat");
> if (!record) {
> @@ -1125,6 +1157,15 @@ int timerlat_top_main(int argc, char *argv[])
> timerlat_aa_destroy();
> if (dma_latency_fd >= 0)
> close(dma_latency_fd);
> +#ifdef HAVE_LIBCPUPOWER_SUPPORT
> + if (params->deepest_idle_state >= -1) {
> + for (i = 0; i < sysconf(_SC_NPROCESSORS_CONF); i++) {
You would think gcc may optimize it, but I don't have that much confidence
it can or would. You may want to change that to:
int nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
for (i = 0; i < nr_cpus; i++) {
Otherwise you may be calling that sysconf() for each iteration of the loop.
-- Steve
> + if (params->cpus && !CPU_ISSET(i,
> ¶ms->monitored_cpus))
> + continue;
> + restore_cpu_idle_disable_state(i);
> + }
> + }
> +#endif /* HAVE_LIBCPUPOWER_SUPPORT */
> trace_events_destroy(&record->trace, params->events);
> params->events = NULL;
> out_free:
> @@ -1134,6 +1175,9 @@ int timerlat_top_main(int argc, char *argv[])
> osnoise_destroy_tool(record);
> osnoise_destroy_tool(top);
> free(params);
> +#ifdef HAVE_LIBCPUPOWER_SUPPORT
> + free_cpu_idle_disable_states();
> +#endif /* HAVE_LIBCPUPOWER_SUPPORT */
> out_exit:
> exit(return_value);
> }
