From patchwork Fri Jun 11 12:41:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Pratik R. Sampat" X-Patchwork-Id: 1490946 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org (client-ip=2404:9400:2:0:216:3eff:fee1:b9f1; helo=lists.ozlabs.org; envelope-from=linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=lwXL1U1R; dkim-atps=neutral Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2404:9400:2:0:216:3eff:fee1:b9f1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4G1gW44vj7z9sXG for ; Fri, 11 Jun 2021 22:43:28 +1000 (AEST) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4G1gW46YKDz3cDf for ; Fri, 11 Jun 2021 22:43:28 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=lwXL1U1R; dkim-atps=neutral X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com; envelope-from=psampat@linux.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=lwXL1U1R; dkim-atps=neutral Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4G1gTj3cdDz3bxZ for ; Fri, 11 Jun 2021 22:42:17 +1000 (AEST) Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 15BCXbCi013278; Fri, 11 Jun 2021 08:42:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=pp1; bh=JhedSqjiHJno7nFv+Mq6xGFzMxPYJSPj48RO97RHbFM=; b=lwXL1U1RJxTNN7wpeg8jseEM5Zrm11Rbk1tXTzjC++mH9GH92khEHrkzEjx8hok/WQmV UH1ZRiPGUTU98FwhHHkYSksIb06ib6WUe56hRfeBz5a8BY/lprDK6PuXVX17ikM5lapF G0XK0RS9aAkIK5l1tyVJW4jLK/G/Ku1NzIIPaGVIx05YROkX4vnnDLvUu/qKpJCWZqrV d955k0Iz8Xu3lyA505w0AEUIl2tVDjn4c+YAofxa7cSbItwlrGz4wkWsMPvlSUfFSdVj G35EFtjbeL8Txrk7MupFd4Qt+8a2xqSHhw2crhCYK+x1M2kg69L4JhxCUK6E/xLdD2x1 Uw== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3947pcgq04-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 11 Jun 2021 08:42:10 -0400 Received: from m0098410.ppops.net (m0098410.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 15BCY43W016082; Fri, 11 Jun 2021 08:42:10 -0400 Received: from ppma04ams.nl.ibm.com (63.31.33a9.ip4.static.sl-reverse.com [169.51.49.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 3947pcgpy4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 11 Jun 2021 08:42:09 -0400 Received: from pps.filterd (ppma04ams.nl.ibm.com [127.0.0.1]) by ppma04ams.nl.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 15BCWbUQ004792; Fri, 11 Jun 2021 12:42:07 GMT Received: from b06avi18626390.portsmouth.uk.ibm.com (b06avi18626390.portsmouth.uk.ibm.com [9.149.26.192]) by ppma04ams.nl.ibm.com with ESMTP id 3900w8becw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 11 Jun 2021 12:42:07 +0000 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06avi18626390.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 15BCf7fR35652026 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 11 Jun 2021 12:41:07 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6F36252067; Fri, 11 Jun 2021 12:41:59 +0000 (GMT) Received: from pratiks-thinkpad.in.ibm.com (unknown [9.85.83.107]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTP id 982735205A; Fri, 11 Jun 2021 12:41:57 +0000 (GMT) From: "Pratik R. Sampat" To: mpe@ellerman.id.au, shuah@kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kselftest@vger.kernel.org, psampat@linux.ibm.com, pratik.r.sampat@gmail.com Subject: [RFC 1/2] powerpc/cpuidle: Extract IPI based and timer based wakeup latency from idle states Date: Fri, 11 Jun 2021 18:11:53 +0530 Message-Id: <20210611124154.56427-2-psampat@linux.ibm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210611124154.56427-1-psampat@linux.ibm.com> References: <20210611124154.56427-1-psampat@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 4rLkOiwQ1o7QlAmkhVGHrnTpQtroRNa1 X-Proofpoint-ORIG-GUID: -FGEv8xzENIjBrC_GDqSohzEYwtQ_UsR X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-06-11_05:2021-06-11, 2021-06-11 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 mlxscore=0 lowpriorityscore=0 phishscore=0 malwarescore=0 bulkscore=0 spamscore=0 suspectscore=0 impostorscore=0 priorityscore=1501 adultscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106110080 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" Introduce a mechanism to fire directed IPIs from a specified source CPU to a specified target CPU and measure the difference in time incurred on wakeup. Also, introduce a mechanism to queue a HR timer on a specified CPU and subsequently measure the time taken to wakeup the CPU. Finally define a simple debugfs interface to control the knobs to fire the IPI and Timer events on specified CPU and view their incurred idle wakeup latencies. Signed-off-by: Pratik R. Sampat --- arch/powerpc/kernel/Makefile | 1 + arch/powerpc/kernel/test-cpuidle_latency.c | 157 +++++++++++++++++++++ lib/Kconfig.debug | 10 ++ 3 files changed, 168 insertions(+) create mode 100644 arch/powerpc/kernel/test-cpuidle_latency.c diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index f66b63e81c3b..56e36e797dd4 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -56,6 +56,7 @@ obj-$(CONFIG_PPC_WATCHDOG) += watchdog.o obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o obj-$(CONFIG_PPC_DAWR) += dawr.o obj-$(CONFIG_PPC_BOOK3S_64) += cpu_setup_ppc970.o cpu_setup_pa6t.o +obj-$(CONFIG_IDLE_LATENCY_SELFTEST) += test-cpuidle_latency.o obj-$(CONFIG_PPC_BOOK3S_64) += cpu_setup_power.o obj-$(CONFIG_PPC_BOOK3S_64) += mce.o mce_power.o obj-$(CONFIG_PPC_BOOK3E_64) += exceptions-64e.o idle_book3e.o diff --git a/arch/powerpc/kernel/test-cpuidle_latency.c b/arch/powerpc/kernel/test-cpuidle_latency.c new file mode 100644 index 000000000000..f138011ac225 --- /dev/null +++ b/arch/powerpc/kernel/test-cpuidle_latency.c @@ -0,0 +1,157 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Module-based API test facility for cpuidle latency using IPIs and timers + */ + +#include +#include +#include + +/* + * IPI based wakeup latencies + * Measure time taken for a CPU to wakeup on a IPI sent from another CPU + * The latency measured also includes the latency of sending the IPI + */ +struct latency { + unsigned int src_cpu; + unsigned int dest_cpu; + ktime_t time_start; + ktime_t time_end; + u64 latency_ns; +} ipi_wakeup; + +static void measure_latency(void *info) +{ + struct latency *v; + ktime_t time_diff; + + v = (struct latency *)info; + v->time_end = ktime_get(); + time_diff = ktime_sub(v->time_end, v->time_start); + v->latency_ns = ktime_to_ns(time_diff); +} + +void run_smp_call_function_test(unsigned int cpu) +{ + ipi_wakeup.src_cpu = smp_processor_id(); + ipi_wakeup.dest_cpu = cpu; + ipi_wakeup.time_start = ktime_get(); + smp_call_function_single(cpu, measure_latency, &ipi_wakeup, 1); +} + +/* + * Timer based wakeup latencies + * Measure time taken for a CPU to wakeup on a timer being armed and fired + */ +struct timer_data { + unsigned int src_cpu; + u64 timeout; + ktime_t time_start; + ktime_t time_end; + struct hrtimer timer; + u64 timeout_diff_ns; +} timer_wakeup; + +static enum hrtimer_restart timer_called(struct hrtimer *hrtimer) +{ + struct timer_data *w; + ktime_t time_diff; + + w = container_of(hrtimer, struct timer_data, timer); + w->time_end = ktime_get(); + + time_diff = ktime_sub(w->time_end, w->time_start); + time_diff = ktime_sub(time_diff, ns_to_ktime(w->timeout)); + w->timeout_diff_ns = ktime_to_ns(time_diff); + return HRTIMER_NORESTART; +} + +static void run_timer_test(unsigned int ns) +{ + hrtimer_init(&timer_wakeup.timer, CLOCK_MONOTONIC, + HRTIMER_MODE_REL); + timer_wakeup.timer.function = timer_called; + timer_wakeup.src_cpu = smp_processor_id(); + timer_wakeup.timeout = ns; + timer_wakeup.time_start = ktime_get(); + + hrtimer_start(&timer_wakeup.timer, ns_to_ktime(ns), + HRTIMER_MODE_REL_PINNED); +} + +static struct dentry *dir; + +static int cpu_read_op(void *data, u64 *dest_cpu) +{ + *dest_cpu = ipi_wakeup.dest_cpu; + return 0; +} + +static int cpu_write_op(void *data, u64 value) +{ + run_smp_call_function_test(value); + return 0; +} +DEFINE_SIMPLE_ATTRIBUTE(ipi_ops, cpu_read_op, cpu_write_op, "%llu\n"); + +static int timeout_read_op(void *data, u64 *timeout) +{ + *timeout = timer_wakeup.timeout; + return 0; +} + +static int timeout_write_op(void *data, u64 value) +{ + run_timer_test(value); + return 0; +} +DEFINE_SIMPLE_ATTRIBUTE(timeout_ops, timeout_read_op, timeout_write_op, "%llu\n"); + +static int __init latency_init(void) +{ + struct dentry *temp; + + dir = debugfs_create_dir("latency_test", 0); + if (!dir) { + pr_alert("latency_test: failed to create /sys/kernel/debug/latency_test\n"); + return -1; + } + temp = debugfs_create_file("ipi_cpu_dest", + 0666, + dir, + NULL, + &ipi_ops); + if (!temp) { + pr_alert("latency_test: failed to create /sys/kernel/debug/ipi_cpu_dest\n"); + return -1; + } + debugfs_create_u64("ipi_latency_ns", 0444, dir, &ipi_wakeup.latency_ns); + debugfs_create_u32("ipi_cpu_src", 0444, dir, &ipi_wakeup.src_cpu); + + temp = debugfs_create_file("timeout_expected_ns", + 0666, + dir, + NULL, + &timeout_ops); + if (!temp) { + pr_alert("latency_test: failed to create /sys/kernel/debug/timeout_expected_ns\n"); + return -1; + } + debugfs_create_u64("timeout_diff_ns", 0444, dir, &timer_wakeup.timeout_diff_ns); + debugfs_create_u32("timeout_cpu_src", 0444, dir, &timer_wakeup.src_cpu); + pr_info("Latency Test module loaded\n"); + return 0; +} + +static void __exit latency_cleanup(void) +{ + pr_info("Cleaning up Latency Test module.\n"); + debugfs_remove_recursive(dir); +} + +module_init(latency_init); +module_exit(latency_cleanup); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("IBM Corporation"); +MODULE_DESCRIPTION("Measuring idle latency for IPIs and Timers"); diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 417c3d3e521b..70264687e0c2 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1513,6 +1513,16 @@ config DEBUG_KOBJECT If you say Y here, some extra kobject debugging messages will be sent to the syslog. +config IDLE_LATENCY_SELFTEST + tristate "Cpuidle latency selftests" + depends on CPU_IDLE + help + This option provides a kernel module that runs tests using the IPI and + timers to measure latency. + + Say M if you want these self tests to build as a module. + Say N if you are unsure. + config DEBUG_KOBJECT_RELEASE bool "kobject release debugging" depends on DEBUG_OBJECTS_TIMERS