Commit c58a3f8c authored by Daniel Bristot de Oliveira's avatar Daniel Bristot de Oliveira Committed by Steven Rostedt (Google)
Browse files

rtla: Automatically move rtla to a house-keeping cpu 

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: default avatarJuri Lelli <juri.lelli@redhat.com>
Signed-off-by: default avatarDaniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 894c29c7

tools/tracing/rtla/src/osnoise_hist.c

+9 −0
Original line number Diff line number Diff line
@@ -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;

tools/tracing/rtla/src/osnoise_top.c

+9 −0
Original line number Diff line number Diff line
@@ -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;

tools/tracing/rtla/src/timerlat_hist.c

+9 −0
Original line number Diff line number Diff line
@@ -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;

tools/tracing/rtla/src/timerlat_top.c

+9 −0
Original line number Diff line number Diff line
@@ -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;

tools/tracing/rtla/src/utils.c

+50 −0
Original line number Diff line number Diff line
@@ -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;

}