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rtla: Automatically move rtla to a house-keeping cpu

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When the user sets -c <cpu-list> try to move rtla out of the <cpu-list>,
even without an -H option. This is useful to avoid having rtla
interfering with the workload.

This works by removing <cpu-list> from rtla's current affinity.

If rtla fails to move itself away it is not that of a problem as this
is an automatic measure.

Link: https://lkml.kernel.org/r/c54304d90c777310fb85a3e658d1449173759aab.1686066600.git.bristot@kernel.org

Cc: William White <chwhite@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Daniel Bristot de Oliveira 2023-06-06 18:12:18 +02:00 committed by Steven Rostedt (Google)
parent 894c29c76b
commit c58a3f8c7f
6 changed files with 87 additions and 0 deletions
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9
tools/tracing/rtla/src/osnoise_hist.c
View file

@ -753,6 +753,15 @@ osnoise_hist_apply_config(struct osnoise_tool *tool, struct osnoise_hist_params
err_msg("Failed to set rtla to the house keeping CPUs\n");
goto out_err;
}
} else if (params->cpus) {
/*
* Even if the user do not set a house-keeping CPU, try to
* move rtla to a CPU set different to the one where the user
* set the workload to run.
*
* No need to check results as this is an automatic attempt.
*/
auto_house_keeping(&params->monitored_cpus);
}
return 0;

9
tools/tracing/rtla/src/osnoise_top.c
View file

@ -582,6 +582,15 @@ osnoise_top_apply_config(struct osnoise_tool *tool, struct osnoise_top_params *p
err_msg("Failed to set rtla to the house keeping CPUs\n");
goto out_err;
}
} else if (params->cpus) {
/*
* Even if the user do not set a house-keeping CPU, try to
* move rtla to a CPU set different to the one where the user
* set the workload to run.
*
* No need to check results as this is an automatic attempt.
*/
auto_house_keeping(&params->monitored_cpus);
}
return 0;

9
tools/tracing/rtla/src/timerlat_hist.c
View file

@ -776,6 +776,15 @@ timerlat_hist_apply_config(struct osnoise_tool *tool, struct timerlat_hist_param
err_msg("Failed to set rtla to the house keeping CPUs\n");
goto out_err;
}
} else if (params->cpus) {
/*
* Even if the user do not set a house-keeping CPU, try to
* move rtla to a CPU set different to the one where the user
* set the workload to run.
*
* No need to check results as this is an automatic attempt.
*/
auto_house_keeping(&params->monitored_cpus);
}
return 0;

9
tools/tracing/rtla/src/timerlat_top.c
View file

@ -619,6 +619,15 @@ timerlat_top_apply_config(struct osnoise_tool *top, struct timerlat_top_params *
err_msg("Failed to set rtla to the house keeping CPUs\n");
goto out_err;
}
} else if (params->cpus) {
/*
* Even if the user do not set a house-keeping CPU, try to
* move rtla to a CPU set different to the one where the user
* set the workload to run.
*
* No need to check results as this is an automatic attempt.
*/
auto_house_keeping(&params->monitored_cpus);
}
return 0;

50
tools/tracing/rtla/src/utils.c
View file

@ -709,3 +709,53 @@ int set_comm_cgroup(const char *comm_prefix, const char *cgroup)
close(cg_fd);
return 0;
}
/**
* auto_house_keeping - Automatically move rtla out of measurement threads
*
* Try to move rtla away from the tracer, if possible.
*
* Returns 1 on success, 0 otherwise.
*/
int auto_house_keeping(cpu_set_t *monitored_cpus)
{
cpu_set_t rtla_cpus, house_keeping_cpus;
int retval;
/* first get the CPUs in which rtla can actually run. */
retval = sched_getaffinity(getpid(), sizeof(rtla_cpus), &rtla_cpus);
if (retval == -1) {
debug_msg("Could not get rtla affinity, rtla might run with the threads!\n");
return 0;
}
/* then check if the existing setup is already good. */
CPU_AND(&house_keeping_cpus, &rtla_cpus, monitored_cpus);
if (!CPU_COUNT(&house_keeping_cpus)) {
debug_msg("rtla and the monitored CPUs do not share CPUs.");
debug_msg("Skipping auto house-keeping\n");
return 1;
}
/* remove the intersection */
CPU_XOR(&house_keeping_cpus, &rtla_cpus, monitored_cpus);
/* get only those that rtla can run */
CPU_AND(&house_keeping_cpus, &house_keeping_cpus, &rtla_cpus);
/* is there any cpu left? */
if (!CPU_COUNT(&house_keeping_cpus)) {
debug_msg("Could not find any CPU for auto house-keeping\n");
return 0;
}
retval = sched_setaffinity(getpid(), sizeof(house_keeping_cpus), &house_keeping_cpus);
if (retval == -1) {
debug_msg("Could not set affinity for auto house-keeping\n");
return 0;
}
debug_msg("rtla automatically moved to an auto house-keeping cpu set\n");
return 1;
}

1
tools/tracing/rtla/src/utils.h
View file

@ -60,6 +60,7 @@ int parse_cpu_set(char *cpu_list, cpu_set_t *set);
int set_comm_sched_attr(const char *comm_prefix, struct sched_attr *attr);
int set_comm_cgroup(const char *comm_prefix, const char *cgroup);
int set_cpu_dma_latency(int32_t latency);
int auto_house_keeping(cpu_set_t *monitored_cpus);
#define ns_to_usf(x) (((double)x/1000))
#define ns_to_per(total, part) ((part * 100) / (double)total)