From patchwork Wed Mar 2 19:01:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12766597 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6456C4332F for ; Wed, 2 Mar 2022 19:04:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244890AbiCBTFU convert rfc822-to-8bit (ORCPT ); Wed, 2 Mar 2022 14:05:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244865AbiCBTFT (ORCPT ); Wed, 2 Mar 2022 14:05:19 -0500 Received: from us-smtp-delivery-44.mimecast.com (us-smtp-delivery-44.mimecast.com [207.211.30.44]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id B66EDBDE7E for ; Wed, 2 Mar 2022 11:04:33 -0800 (PST) Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-103-RxvgnynMN5ePsk1nYiuWXA-1; Wed, 02 Mar 2022 14:04:29 -0500 X-MC-Unique: RxvgnynMN5ePsk1nYiuWXA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 38A941091DA0; Wed, 2 Mar 2022 19:04:27 +0000 (UTC) Received: from x1.com (unknown [10.22.32.168]) by smtp.corp.redhat.com (Postfix) with ESMTP id 18EC919C59; Wed, 2 Mar 2022 19:04:24 +0000 (UTC) From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , Jonathan Corbet , Clark Williams , Juri Lelli , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V3 14/15] rtla/timerlat: Add --dma-latency option Date: Wed, 2 Mar 2022 20:01:39 +0100 Message-Id: <72ddb0d913459f13217086dadafad88a7c46dd28.1646247211.git.bristot@kernel.org> In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=bristot@kernel.org X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org 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. Cc: Daniel Bristot de Oliveira Cc: Steven Rostedt Cc: Jonathan Corbet Signed-off-by: Daniel Bristot de Oliveira --- .../tools/rtla/common_timerlat_options.rst | 5 +++ 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 + 5 files changed, 91 insertions(+), 4 deletions(-) diff --git a/Documentation/tools/rtla/common_timerlat_options.rst b/Documentation/tools/rtla/common_timerlat_options.rst index 14a24a121f5d..bacdea6de7a3 100644 --- a/Documentation/tools/rtla/common_timerlat_options.rst +++ b/Documentation/tools/rtla/common_timerlat_options.rst @@ -21,3 +21,8 @@ Save the stack trace at the *IRQ* if a *Thread* latency is higher than the argument in us. + +**--dma-latency** *us* + Set the /dev/cpu_dma_latency to *us*, aiming to bound exit from idle latencies. + *cyclictest* sets this value to *0* by default, use **--dma-latency** *0* to have + similar results. 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);