From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-20.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14A72C433DB for ; Tue, 9 Feb 2021 15:46:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D9E4164DFF for ; Tue, 9 Feb 2021 15:46:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232614AbhBIPq0 (ORCPT ); Tue, 9 Feb 2021 10:46:26 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:45032 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232548AbhBIPpu (ORCPT ); Tue, 9 Feb 2021 10:45:50 -0500 Date: Tue, 09 Feb 2021 15:45:06 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1612885507; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5Dq3ZQ/5Szkm5G+i8hAJ8U2bM9k6hjZsGXQtEcnj7Js=; b=w+kGFwWoUs9wxUjXUHa0TocssQl94mz08kuDyf6TDdew938aZ3UJcAYdWXEjrhLKcHpMHq ma8PkUzAp3YJM+0eEx8wEa3Z5owlwJvW3G8qiasj2jsSZysngc15Ns0bE4mjyY+euRcOu4 sMnMWL+Df4I4sB3ud4Q/htK+V8PSPqk6hnRXnvMef6a/68R2MmhsJPMZT1jSCf98op2XNO X4uA10zaObtRK1jaB1kxx5EyYUUCK7clIGfFhTKSG8Z35Oaq99dcZqTrlWJ/WPyzr6tUHn pOFUute5hl24wXla+JXuULrY9Yr6rOP6eTS/qQPhnDnvjeZDhL0Vy1JP3bHE7w== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1612885507; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5Dq3ZQ/5Szkm5G+i8hAJ8U2bM9k6hjZsGXQtEcnj7Js=; b=vYNk8rtsifL9zlId3SmfwwHDotJcCk4TxD11Kscz/tshkSHIWA/IEKlmagWOrEaYCrro2A U/NM+x0tYkWURPCg== From: "tip-bot2 for Peter Zijlstra" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] sched: Add /debug/sched_preempt Cc: "Peter Zijlstra (Intel)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: References: MIME-Version: 1.0 Message-ID: <161288550683.23325.6904383371578790672.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: b57f3de85c79f9fbfe2fd84cc6ba548e4e73d02d Gitweb: https://git.kernel.org/tip/b57f3de85c79f9fbfe2fd84cc6ba548e4e73d02d Author: Peter Zijlstra AuthorDate: Fri, 22 Jan 2021 13:01:58 +01:00 Committer: Peter Zijlstra CommitterDate: Tue, 09 Feb 2021 16:31:03 +01:00 sched: Add /debug/sched_preempt Add a debugfs file to muck about with the preempt mode at runtime. Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/YAsGiUYf6NyaTplX@hirez.programming.kicks-ass.net --- kernel/sched/core.c | 135 ++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 126 insertions(+), 9 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 220393d..cb226f7 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5349,37 +5349,154 @@ EXPORT_STATIC_CALL(preempt_schedule_notrace); * preempt_schedule_notrace <- preempt_schedule_notrace * irqentry_exit_cond_resched <- irqentry_exit_cond_resched */ -static int __init setup_preempt_mode(char *str) + +enum { + preempt_dynamic_none = 0, + preempt_dynamic_voluntary, + preempt_dynamic_full, +}; + +static int preempt_dynamic_mode = preempt_dynamic_full; + +static int sched_dynamic_mode(const char *str) { - if (!strcmp(str, "none")) { + if (!strcmp(str, "none")) + return 0; + + if (!strcmp(str, "voluntary")) + return 1; + + if (!strcmp(str, "full")) + return 2; + + return -1; +} + +static void sched_dynamic_update(int mode) +{ + /* + * Avoid {NONE,VOLUNTARY} -> FULL transitions from ever ending up in + * the ZERO state, which is invalid. + */ + static_call_update(cond_resched, __cond_resched); + static_call_update(might_resched, __cond_resched); + static_call_update(preempt_schedule, __preempt_schedule_func); + static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func); + static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched); + + switch (mode) { + case preempt_dynamic_none: static_call_update(cond_resched, __cond_resched); static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0); static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL); static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL); static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL); - pr_info("Dynamic Preempt: %s\n", str); - } else if (!strcmp(str, "voluntary")) { + pr_info("Dynamic Preempt: none\n"); + break; + + case preempt_dynamic_voluntary: static_call_update(cond_resched, __cond_resched); static_call_update(might_resched, __cond_resched); static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL); static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL); static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL); - pr_info("Dynamic Preempt: %s\n", str); - } else if (!strcmp(str, "full")) { + pr_info("Dynamic Preempt: voluntary\n"); + break; + + case preempt_dynamic_full: static_call_update(cond_resched, (typeof(&__cond_resched)) __static_call_return0); static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0); static_call_update(preempt_schedule, __preempt_schedule_func); static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func); static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched); - pr_info("Dynamic Preempt: %s\n", str); - } else { - pr_warn("Dynamic Preempt: Unsupported preempt mode %s, default to full\n", str); + pr_info("Dynamic Preempt: full\n"); + break; + } + + preempt_dynamic_mode = mode; +} + +static int __init setup_preempt_mode(char *str) +{ + int mode = sched_dynamic_mode(str); + if (mode < 0) { + pr_warn("Dynamic Preempt: unsupported mode: %s\n", str); return 1; } + + sched_dynamic_update(mode); return 0; } __setup("preempt=", setup_preempt_mode); +#ifdef CONFIG_SCHED_DEBUG + +static ssize_t sched_dynamic_write(struct file *filp, const char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + char buf[16]; + int mode; + + if (cnt > 15) + cnt = 15; + + if (copy_from_user(&buf, ubuf, cnt)) + return -EFAULT; + + buf[cnt] = 0; + mode = sched_dynamic_mode(strstrip(buf)); + if (mode < 0) + return mode; + + sched_dynamic_update(mode); + + *ppos += cnt; + + return cnt; +} + +static int sched_dynamic_show(struct seq_file *m, void *v) +{ + static const char * preempt_modes[] = { + "none", "voluntary", "full" + }; + int i; + + for (i = 0; i < ARRAY_SIZE(preempt_modes); i++) { + if (preempt_dynamic_mode == i) + seq_puts(m, "("); + seq_puts(m, preempt_modes[i]); + if (preempt_dynamic_mode == i) + seq_puts(m, ")"); + + seq_puts(m, " "); + } + + seq_puts(m, "\n"); + return 0; +} + +static int sched_dynamic_open(struct inode *inode, struct file *filp) +{ + return single_open(filp, sched_dynamic_show, NULL); +} + +static const struct file_operations sched_dynamic_fops = { + .open = sched_dynamic_open, + .write = sched_dynamic_write, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +static __init int sched_init_debug_dynamic(void) +{ + debugfs_create_file("sched_preempt", 0644, NULL, NULL, &sched_dynamic_fops); + return 0; +} +late_initcall(sched_init_debug_dynamic); + +#endif /* CONFIG_SCHED_DEBUG */ #endif /* CONFIG_PREEMPT_DYNAMIC */