From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0896969968 for ; Fri, 1 Mar 2024 08:14:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709280856; cv=none; b=YI4m9T0fTLJqaT98zW54qWOpc5ngCkLUfqpJ5XvUkxBRpG4k9UGg5jlNABPlfIfVRlQcLUkelSoIeXHCrRa/CRMldfpRZ9hPWol/RCt02VQ2cQji8CBq39zUDj+56WMZIxuYkXq+Y08BC19BzTpf2tN6rzYhwSMnP9miAQ2eRU8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709280856; c=relaxed/simple; bh=jaP5tyZRYYfMcaJ7grKsHD19hayDCXPmT0t3bv6/8bY=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=MBBcq+TIIZO9kuuTessy5MjfXMEhxRkvL6SDPwjp4Wa255NbbSgHxfMF6TAw1wjxqTYq3ZNhYgHW40TPYTrH9XcFanIXMoUc02oAOUD6XKtMIaSStVOYpJX4hugC6Sx65LbLQijM02KtmCrEnIZtwYyx3qXHOBd9tMBldpmd87g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=reiKqrSc; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=/AiQxsPe; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="reiKqrSc"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="/AiQxsPe" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1709280852; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XUXcVZzlTt019jlXW5vVIeqdQ7GFrCPz8tzw8VHsJvc=; b=reiKqrScZQuDrP55pZfFXab9Y1omzvIjkor1bG7gh7QnekkTD/xJFJkqBRaEA6qn9fTmwl oLZKRLpGil5H1f8K17BjaSHLQNzFMnIyIIH9lT+oKSkkd5khFF28d0hsKTjteGUMKQq//z TTMY9aoH66EhJ++ClqY39L1haWplsmUb5eg3mlpeYDwaA1w5SThZW/kJ1w5mWtUkBiKmcH +NC6O4TJNMW0u460D3rZVcvh7Csi+E2sz05MI4U3iALOWZY6/cm+D+T7dISKfcMToFdRmU B3WrrcKKN0G/LdsA4I1mIfbHoMsEhEoAvIZqzRmdZ59PWF3q9IeV6w3TQHfGuw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1709280852; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XUXcVZzlTt019jlXW5vVIeqdQ7GFrCPz8tzw8VHsJvc=; b=/AiQxsPeY9WI5tmRqkD1+p6T/kT+YtfPLxS/AssP7CS/4ev4cnOT8BVBJqM7fkIE6ndhTR 0jjGFF/PG6Er0FCA== To: LKML Cc: x86@kernel.org, Steven Rostedt , "Paul E. McKenney" Subject: Re: [patch 6/6] x86/idle: Select idle routine only once In-Reply-To: <20240229142248.582321500@linutronix.de> References: <20240229141407.283316443@linutronix.de> <20240229142248.582321500@linutronix.de> Date: Fri, 01 Mar 2024 09:14:11 +0100 Message-ID: <87h6hq74j0.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Thu, Feb 29 2024 at 15:23, Thomas Gleixner wrote: > > - if (x86_idle_set()) > - return; > - Bah. With XEN=n this results in a defined but not used warning. Updated version below. --- Subject: x86/idle: Select idle routine only once From: Thomas Gleixner Date: Wed, 28 Feb 2024 23:20:32 +0100 The idle routine selection is done on every CPU bringup operation and has a guard in place which is effective after the first invocation, which is a pointless exercise. Invoke it once on the boot CPU and mark the related functions __init. Signed-off-by: Thomas Gleixner --- V1a: Move x86_idle_set() into the only usage site (0day) --- arch/x86/include/asm/processor.h | 2 +- arch/x86/kernel/cpu/common.c | 4 ++-- arch/x86/kernel/process.c | 18 +++++------------- 3 files changed, 8 insertions(+), 16 deletions(-) --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -555,7 +555,7 @@ static inline void load_sp0(unsigned lon unsigned long __get_wchan(struct task_struct *p); -extern void select_idle_routine(const struct cpuinfo_x86 *c); +extern void select_idle_routine(void); extern void amd_e400_c1e_apic_setup(void); extern unsigned long boot_option_idle_override; --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1938,8 +1938,6 @@ static void identify_cpu(struct cpuinfo_ /* Init Machine Check Exception if available. */ mcheck_cpu_init(c); - select_idle_routine(c); - #ifdef CONFIG_NUMA numa_add_cpu(smp_processor_id()); #endif @@ -2343,6 +2341,8 @@ void __init arch_cpu_finalize_init(void) { identify_boot_cpu(); + select_idle_routine(); + /* * identify_boot_cpu() initialized SMT support information, let the * core code know. --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -748,11 +748,6 @@ EXPORT_SYMBOL(default_idle); DEFINE_STATIC_CALL_NULL(x86_idle, default_idle); -static bool x86_idle_set(void) -{ - return !!static_call_query(x86_idle); -} - #ifndef CONFIG_SMP static inline void __noreturn play_dead(void) { @@ -783,10 +778,9 @@ EXPORT_SYMBOL_GPL(arch_cpu_idle); #ifdef CONFIG_XEN bool xen_set_default_idle(void) { - bool ret = x86_idle_set(); + bool ret = !!static_call_query(x86_idle); static_call_update(x86_idle, default_idle); - return ret; } #endif @@ -853,8 +847,9 @@ void __noreturn stop_this_cpu(void *dumm * Do not prefer MWAIT if MONITOR instruction has a bug or idle=nomwait * is passed to kernel commandline parameter. */ -static bool prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c) +static __init bool prefer_mwait_c1_over_halt(void) { + const struct cpuinfo_x86 *c = &boot_cpu_data; u32 eax, ebx, ecx, edx; /* If override is enforced on the command line, fall back to HALT. */ @@ -908,7 +903,7 @@ static __cpuidle void mwait_idle(void) __current_clr_polling(); } -void select_idle_routine(const struct cpuinfo_x86 *c) +void __init select_idle_routine(void) { if (boot_option_idle_override == IDLE_POLL) { if (IS_ENABLED(CONFIG_SMP) && smp_num_siblings > 1) @@ -916,10 +911,7 @@ void select_idle_routine(const struct cp return; } - if (x86_idle_set()) - return; - - if (prefer_mwait_c1_over_halt(c)) { + if (prefer_mwait_c1_over_halt()) { pr_info("using mwait in idle threads\n"); static_call_update(x86_idle, mwait_idle); } else if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) {