From 7d0dc9576dc3817c483b408715e506c3e9f37bed Mon Sep 17 00:00:00 2001 From: Daniel Bristot de Oliveira Date: Wed, 2 Mar 2022 20:01:39 +0100 Subject: rtla/timerlat: Add --dma-latency option Add the --dma-latency to set /dev/cpu_dma_latency to the specified value, this aims to avoid having exit from idle states latencies that could be influencing the analysis. Link: https://lkml.kernel.org/r/72ddb0d913459f13217086dadafad88a7c46dd28.1646247211.git.bristot@kernel.org Cc: Daniel Bristot de Oliveira Cc: Clark Williams Cc: Juri Lelli Cc: Jonathan Corbet Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (Google) --- tools/tracing/rtla/src/timerlat_hist.c | 28 ++++++++++++++++++++++++++-- tools/tracing/rtla/src/timerlat_top.c | 28 ++++++++++++++++++++++++++-- tools/tracing/rtla/src/utils.c | 33 +++++++++++++++++++++++++++++++++ tools/tracing/rtla/src/utils.h | 1 + 4 files changed, 86 insertions(+), 4 deletions(-) (limited to 'tools/tracing') diff --git a/tools/tracing/rtla/src/timerlat_hist.c b/tools/tracing/rtla/src/timerlat_hist.c index 17188ccb6e8b..0f6ce80a198a 100644 --- a/tools/tracing/rtla/src/timerlat_hist.c +++ b/tools/tracing/rtla/src/timerlat_hist.c @@ -28,6 +28,7 @@ struct timerlat_hist_params { int output_divisor; int duration; int set_sched; + int dma_latency; struct sched_attr sched_param; struct trace_events *events; @@ -432,7 +433,7 @@ 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 ] [--trigger ] [-c cpu-list] \\", " [-P priority] [-E N] [-b N] [--no-irq] [--no-thread] [--no-header] [--no-summary] \\", - " [--no-index] [--with-zeros]", + " [--no-index] [--with-zeros] [--dma-latency us]", "", " -h/--help: print this menu", " -a/--auto: set automatic trace mode, stopping the session if argument in us latency is hit", @@ -456,6 +457,7 @@ static void timerlat_hist_usage(char *usage) " --no-summary: do not print summary", " --no-index: do not print index", " --with-zeros: print zero only entries", + " --dma-latency us: set /dev/cpu_dma_latency latency to reduce exit from idle latency", " -P/--priority o:prio|r:prio|f:prio|d:runtime:period : set scheduling parameters", " o:prio - use SCHED_OTHER with prio", " r:prio - use SCHED_RR with prio", @@ -492,6 +494,9 @@ static struct timerlat_hist_params if (!params) exit(1); + /* disabled by default */ + params->dma_latency = -1; + /* display data in microseconds */ params->output_divisor = 1000; params->bucket_size = 1; @@ -522,13 +527,14 @@ static struct timerlat_hist_params {"with-zeros", no_argument, 0, '5'}, {"trigger", required_argument, 0, '6'}, {"filter", required_argument, 0, '7'}, + {"dma-latency", required_argument, 0, '8'}, {0, 0, 0, 0} }; /* getopt_long stores the option index here. */ int option_index = 0; - c = getopt_long(argc, argv, "a:c:b:d:e:E:Dhi:np:P:s:t::T:0123456:7:", + c = getopt_long(argc, argv, "a:c:b:d:e:E:Dhi:np:P:s:t::T:0123456:7:8:", long_options, &option_index); /* detect the end of the options. */ @@ -659,6 +665,13 @@ static struct timerlat_hist_params timerlat_hist_usage("--filter requires a previous -e\n"); } break; + case '8': + params->dma_latency = get_llong_from_str(optarg); + if (params->dma_latency < 0 || params->dma_latency > 10000) { + err_msg("--dma-latency needs to be >= 0 and < 10000"); + exit(EXIT_FAILURE); + } + break; default: timerlat_hist_usage("Invalid option"); } @@ -791,6 +804,7 @@ int timerlat_hist_main(int argc, char *argv[]) struct osnoise_tool *record = NULL; struct osnoise_tool *tool = NULL; struct trace_instance *trace; + int dma_latency_fd = -1; int return_value = 1; int retval; @@ -826,6 +840,14 @@ int timerlat_hist_main(int argc, char *argv[]) } } + if (params->dma_latency >= 0) { + dma_latency_fd = set_cpu_dma_latency(params->dma_latency); + if (dma_latency_fd < 0) { + err_msg("Could not set /dev/cpu_dma_latency.\n"); + goto out_hist; + } + } + trace_instance_start(trace); if (params->trace_output) { @@ -878,6 +900,8 @@ int timerlat_hist_main(int argc, char *argv[]) } out_hist: + if (dma_latency_fd >= 0) + close(dma_latency_fd); trace_events_destroy(&record->trace, params->events); params->events = NULL; timerlat_free_histogram(tool->data); diff --git a/tools/tracing/rtla/src/timerlat_top.c b/tools/tracing/rtla/src/timerlat_top.c index bf2a50350e61..53f4cdfd395e 100644 --- a/tools/tracing/rtla/src/timerlat_top.c +++ b/tools/tracing/rtla/src/timerlat_top.c @@ -29,6 +29,7 @@ struct timerlat_top_params { int duration; int quiet; int set_sched; + int dma_latency; struct sched_attr sched_param; struct trace_events *events; }; @@ -269,7 +270,7 @@ 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 ] [--trigger ] [-c cpu-list] \\", - " [-P priority]", + " [-P priority] [--dma-latency us]", "", " -h/--help: print this menu", " -a/--auto: set automatic trace mode, stopping the session if argument in us latency is hit", @@ -286,6 +287,7 @@ static void timerlat_top_usage(char *usage) " --trigger : enable a trace event trigger to the previous -e event", " -n/--nano: display data in nanoseconds", " -q/--quiet print only a summary at the end", + " --dma-latency us: set /dev/cpu_dma_latency latency to reduce exit from idle latency", " -P/--priority o:prio|r:prio|f:prio|d:runtime:period : set scheduling parameters", " o:prio - use SCHED_OTHER with prio", " r:prio - use SCHED_RR with prio", @@ -322,6 +324,9 @@ static struct timerlat_top_params if (!params) exit(1); + /* disabled by default */ + params->dma_latency = -1; + /* display data in microseconds */ params->output_divisor = 1000; @@ -343,13 +348,14 @@ static struct timerlat_top_params {"trace", optional_argument, 0, 't'}, {"trigger", required_argument, 0, '0'}, {"filter", required_argument, 0, '1'}, + {"dma-latency", required_argument, 0, '2'}, {0, 0, 0, 0} }; /* getopt_long stores the option index here. */ int option_index = 0; - c = getopt_long(argc, argv, "a:c:d:De:hi:np:P:qs:t::T:0:1:", + c = getopt_long(argc, argv, "a:c:d:De:hi:np:P:qs:t::T:0:1:2:", long_options, &option_index); /* detect the end of the options. */ @@ -454,6 +460,13 @@ static struct timerlat_top_params timerlat_top_usage("--filter requires a previous -e\n"); } break; + case '2': /* dma-latency */ + params->dma_latency = get_llong_from_str(optarg); + if (params->dma_latency < 0 || params->dma_latency > 10000) { + err_msg("--dma-latency needs to be >= 0 and < 10000"); + exit(EXIT_FAILURE); + } + break; default: timerlat_top_usage("Invalid option"); } @@ -582,6 +595,7 @@ int timerlat_top_main(int argc, char *argv[]) struct osnoise_tool *record = NULL; struct osnoise_tool *top = NULL; struct trace_instance *trace; + int dma_latency_fd = -1; int return_value = 1; int retval; @@ -617,6 +631,14 @@ int timerlat_top_main(int argc, char *argv[]) } } + if (params->dma_latency >= 0) { + dma_latency_fd = set_cpu_dma_latency(params->dma_latency); + if (dma_latency_fd < 0) { + err_msg("Could not set /dev/cpu_dma_latency.\n"); + goto out_top; + } + } + trace_instance_start(trace); if (params->trace_output) { @@ -673,6 +695,8 @@ int timerlat_top_main(int argc, char *argv[]) } out_top: + if (dma_latency_fd >= 0) + close(dma_latency_fd); trace_events_destroy(&record->trace, params->events); params->events = NULL; timerlat_free_top(top->data); diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c index ffaf8ec84001..da2b590edaed 100644 --- a/tools/tracing/rtla/src/utils.c +++ b/tools/tracing/rtla/src/utils.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include @@ -431,3 +432,35 @@ int parse_prio(char *arg, struct sched_attr *sched_param) } return 0; } + +/* + * set_cpu_dma_latency - set the /dev/cpu_dma_latecy + * + * This is used to reduce the exit from idle latency. The value + * will be reset once the file descriptor of /dev/cpu_dma_latecy + * is closed. + * + * Return: the /dev/cpu_dma_latecy file descriptor + */ +int set_cpu_dma_latency(int32_t latency) +{ + int retval; + int fd; + + fd = open("/dev/cpu_dma_latency", O_RDWR); + if (fd < 0) { + err_msg("Error opening /dev/cpu_dma_latency\n"); + return -1; + } + + retval = write(fd, &latency, 4); + if (retval < 1) { + err_msg("Error setting /dev/cpu_dma_latency\n"); + close(fd); + return -1; + } + + debug_msg("Set /dev/cpu_dma_latency to %d\n", latency); + + return fd; +} diff --git a/tools/tracing/rtla/src/utils.h b/tools/tracing/rtla/src/utils.h index 9aa962319ca2..fa08e374870a 100644 --- a/tools/tracing/rtla/src/utils.h +++ b/tools/tracing/rtla/src/utils.h @@ -54,3 +54,4 @@ struct sched_attr { int parse_prio(char *arg, struct sched_attr *sched_param); int set_comm_sched_attr(const char *comm, struct sched_attr *attr); +int set_cpu_dma_latency(int32_t latency); -- cgit v1.2.3