From patchwork Mon Sep 11 05:36:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aboorva Devarajan X-Patchwork-Id: 1832105 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.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=ddoUXFYQ; dkim-atps=neutral Authentication-Results: legolas.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+incoming=patchwork.ozlabs.org@lists.ozlabs.org; receiver=patchwork.ozlabs.org) 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 ECDSA (secp384r1)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4Rkb8l4z03z1yhL for ; Mon, 11 Sep 2023 15:37:59 +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=ddoUXFYQ; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Rkb8l3sxXz3cHT for ; Mon, 11 Sep 2023 15:37:59 +1000 (AEST) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org 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=ddoUXFYQ; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=linux.vnet.ibm.com (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com; envelope-from=aboorvad@linux.vnet.ibm.com; receiver=lists.ozlabs.org) Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 4Rkb7S4BS9z2yN3 for ; Mon, 11 Sep 2023 15:36:52 +1000 (AEST) Received: from pps.filterd (m0360072.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 38B5IDO8011185; Mon, 11 Sep 2023 05:36:37 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=pp1; bh=yOBGGkftmUVXsigCbpMtDoFnGqFkcfJLGVO8U9fKSms=; b=ddoUXFYQ5fTcScvkwvGSWNHPsjyl5dLtHncF95ZakORm9/Yj+h3G0eQInWDgi5Auauzb 8g9b0Cj6Q2Gj834dFuxHQ1ujGwfyTgkxOOK6DQo1IMRmrmtYl7z6mcQyUbEwPR4+RyQo pLpM8f5LaRGgGGFfMZjJZzUdrV2j0BLVNehpZwSObMBkFtLHg8EBgXTBPp21QRix8Oz7 yIHX/+qSnCbk7qo1xtQI2AyFQ57GL45wqh7/JBE0jSh1/7XUe43xn1MFGXxR05SAfCK2 nCUtc43rXPZWsHwux4dnXb0NmV5WOQ3NXwo/xBQDhamCresqFEXtnkbvtkIZt8pbE6Q5 LQ== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3t1vmarehw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 11 Sep 2023 05:36:36 +0000 Received: from m0360072.ppops.net (m0360072.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 38B5PNFH032616; Mon, 11 Sep 2023 05:36:35 GMT Received: from ppma22.wdc07v.mail.ibm.com (5c.69.3da9.ip4.static.sl-reverse.com [169.61.105.92]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3t1vmareej-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 11 Sep 2023 05:36:34 +0000 Received: from pps.filterd (ppma22.wdc07v.mail.ibm.com [127.0.0.1]) by ppma22.wdc07v.mail.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 38B4ALoW012064; Mon, 11 Sep 2023 05:36:33 GMT Received: from smtprelay07.fra02v.mail.ibm.com ([9.218.2.229]) by ppma22.wdc07v.mail.ibm.com (PPS) with ESMTPS id 3t13dy8aem-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 11 Sep 2023 05:36:33 +0000 Received: from smtpav01.fra02v.mail.ibm.com (smtpav01.fra02v.mail.ibm.com [10.20.54.100]) by smtprelay07.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 38B5aVL562521708 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 11 Sep 2023 05:36:31 GMT Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6597120043; Mon, 11 Sep 2023 05:36:31 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 970DE20040; Mon, 11 Sep 2023 05:36:28 +0000 (GMT) Received: from li-34d1fccc-27cd-11b2-a85c-c167793e56f7.ibm.com.com (unknown [9.171.42.194]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 11 Sep 2023 05:36:28 +0000 (GMT) From: Aboorva Devarajan To: aboorvad@linux.vnet.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, rmclure@linux.ibm.com, arnd@arndb.de, joel@jms.id.au, shuah@kernel.org, linux-kselftest@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, pratik.r.sampat@gmail.com Subject: [RFC v3 1/2] powerpc/cpuidle: cpuidle wakeup latency based on IPI and timer events Date: Mon, 11 Sep 2023 11:06:19 +0530 Message-Id: <20230911053620.87973-2-aboorvad@linux.vnet.ibm.com> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20230911053620.87973-1-aboorvad@linux.vnet.ibm.com> References: <20230911053620.87973-1-aboorvad@linux.vnet.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: PLUT1YDpeMcFDNn2PSKZMJCMBr2QSlyW X-Proofpoint-ORIG-GUID: l-yKBu74eaKsFSG7_FLkjB3UfaS3wb8k X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.957,Hydra:6.0.601,FMLib:17.11.176.26 definitions=2023-09-11_03,2023-09-05_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 priorityscore=1501 impostorscore=0 spamscore=0 adultscore=0 lowpriorityscore=0 bulkscore=0 mlxscore=0 clxscore=1015 mlxlogscore=999 phishscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2308100000 definitions=main-2309110051 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: , Cc: sshegde@linux.vnet.ibm.com, srikar@linux.vnet.ibm.com Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Pratik R. Sampat Introduce a mechanism to fire directed IPIs from a source CPU to a specified target CPU and measure the time incurred on waking up the target CPU in response. Also, introduce a mechanism to queue a hrtimer on a specified CPU and subsequently measure the time taken to wakeup the CPU. Define a simple debugfs interface that allows for adjusting the settings to trigger IPI and timer events on a designated CPU, and to observe the resulting cpuidle wakeup latencies. Reviewed-by: Srikar Dronamraju Signed-off-by: Pratik R. Sampat Signed-off-by: Aboorva Devarajan --- arch/powerpc/Kconfig.debug | 10 ++ arch/powerpc/kernel/Makefile | 1 + arch/powerpc/kernel/test_cpuidle_latency.c | 154 +++++++++++++++++++++ 3 files changed, 165 insertions(+) create mode 100644 arch/powerpc/kernel/test_cpuidle_latency.c diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug index 2a54fadbeaf5..e175fc3028ac 100644 --- a/arch/powerpc/Kconfig.debug +++ b/arch/powerpc/Kconfig.debug @@ -391,3 +391,13 @@ config KASAN_SHADOW_OFFSET default 0xe0000000 if PPC32 default 0xa80e000000000000 if PPC_BOOK3S_64 default 0xa8001c0000000000 if PPC_BOOK3E_64 + +config CPUIDLE_LATENCY_SELFTEST + tristate "Cpuidle latency selftests" + depends on CPU_IDLE + help + Provides a kernel module that run tests using the IPI and + timers to measure cpuidle latency. + + Say M if you want these self tests to build as a module. + Say N if you are unsure. diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index 2919433be355..3c5a576bbcf2 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -94,6 +94,7 @@ obj-$(CONFIG_PPC_BARRIER_NOSPEC) += security.o obj-$(CONFIG_PPC64) += vdso64_wrapper.o obj-$(CONFIG_ALTIVEC) += vecemu.o obj-$(CONFIG_PPC_BOOK3S_IDLE) += idle_book3s.o +obj-$(CONFIG_CPUIDLE_LATENCY_SELFTEST) += test_cpuidle_latency.o procfs-y := proc_powerpc.o obj-$(CONFIG_PROC_FS) += $(procfs-y) rtaspci-$(CONFIG_PPC64)-$(CONFIG_PCI) := rtas_pci.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..c932222a8f76 --- /dev/null +++ b/arch/powerpc/kernel/test_cpuidle_latency.c @@ -0,0 +1,154 @@ +// 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 = (struct latency *)info; + ktime_t time_diff; + + 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 hrtimer_callback(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 = hrtimer_callback; + 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; +} + +/* + * Send a directed IPI from the current CPU (source) to the destination CPU and + * measure the latency on wakeup. + */ +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; +} + +/* Queue a hrtimer on a specified desitination CPU and measure the time taken to + * wakeup the CPU. + */ +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", arch_debugfs_dir); + if (!dir) { + pr_alert("latency_test: failed to create /sys/kernel/debug/powerpc/latency_test\n"); + return -1; + } + temp = debugfs_create_file("ipi_cpu_dest", 0644, dir, NULL, &ipi_ops); + if (!temp) { + pr_alert("latency_test: failed to create /sys/kernel/debug/powerpc/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", 0644, dir, NULL, &timeout_ops); + if (!temp) { + pr_alert("latency_test: failed to create /sys/kernel/debug/powerpc/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");