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=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,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 C2FBAC56202 for ; Mon, 23 Nov 2020 13:55:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 77EAF2080A for ; Mon, 23 Nov 2020 13:55:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388855AbgKWNy7 (ORCPT ); Mon, 23 Nov 2020 08:54:59 -0500 Received: from mail-ot1-f68.google.com ([209.85.210.68]:36936 "EHLO mail-ot1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733086AbgKWNy7 (ORCPT ); Mon, 23 Nov 2020 08:54:59 -0500 Received: by mail-ot1-f68.google.com with SMTP id l36so15950960ota.4 for ; Mon, 23 Nov 2020 05:54:58 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Tq96Nh1Co8RcOllLdFfkMwlqyVvuQ4D6bMKyZbmcJ3g=; b=EUGHKLCNqRN5xveb76D2hNmIYyQsfKmYVKcTz4vJwAmvSRClKXDY8/P+Fr3wWHSnXA lPgj3HOcrXZc8iYGg0LH1eQ7K1oBLXH9/TVhZV0OxM6yKVi080o3lRwM5MCXn6DuZ8NX uwu75AuH05n3eY+5WG3kKPOEZSiYaUR6KcHe+Pge6vD6jIt9u1sSh7W/VOrjrSI4Xxqx OT+/Wnv/SfyLgcnKYL7XCwFFvSSsJyZThHzs1NJBkDZhQUBAr2i1KLNVwX9dC/IUGmcw xMzhsJs4/tPjZ+ZiE7ZSTIdlhOgGFn63fQBCIxYV+usCXDvZq3rIkVLJ9QUtV+rZhAJT Jskw== X-Gm-Message-State: AOAM532hB0+IQrtkasFcjYO3UpYzYIQzyaMj2FRobOTC5oMQV2tYhV4K 9qyGulb6vJZR87ts06c5InCPy6f84qsxpYnWmn+Ceb3I/zI= X-Google-Smtp-Source: ABdhPJzXXez4p3pf928DPueHy/3kYrLgerW/TZwPzeO9qBSvS35nNwG6l6I5VyAWxg7CBO1/Dl2/8WmECn9XGxZqjoY= X-Received: by 2002:a05:6830:2385:: with SMTP id l5mr12789502ots.321.1606139698218; Mon, 23 Nov 2020 05:54:58 -0800 (PST) MIME-Version: 1.0 References: <20201120114145.197714127@infradead.org> <20201120114925.652731270@infradead.org> <20201123134618.GL3021@hirez.programming.kicks-ass.net> In-Reply-To: <20201123134618.GL3021@hirez.programming.kicks-ass.net> From: "Rafael J. Wysocki" Date: Mon, 23 Nov 2020 14:54:47 +0100 Message-ID: Subject: Re: [PATCH 2/2] intel_idle: Fix intel_idle() vs tracing To: Peter Zijlstra Cc: "Rafael J. Wysocki" , Viresh Kumar , Ingo Molnar , "the arch/x86 maintainers" , Mark Rutland , Will Deacon , svens@linux.ibm.com, Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 23, 2020 at 2:46 PM Peter Zijlstra wrote: > > On Mon, Nov 23, 2020 at 11:26:39AM +0100, Rafael J. Wysocki wrote: > > On Fri, Nov 20, 2020 at 12:50 PM Peter Zijlstra wrote: > > > > > > cpuidle->enter() callbacks should not call into tracing because RCU > > > has already been disabled. Instead of doing the broadcast thing > > > itself, simply advertise to the cpuidle core that those states stop > > > the timer. > > > > > > Signed-off-by: Peter Zijlstra (Intel) > > > --- > > > drivers/idle/intel_idle.c | 37 ++++++++++++++++++++----------------- > > > 1 file changed, 20 insertions(+), 17 deletions(-) > > > > > > --- a/drivers/idle/intel_idle.c > > > +++ b/drivers/idle/intel_idle.c > > > @@ -126,26 +126,9 @@ static __cpuidle int intel_idle(struct c > > > struct cpuidle_state *state = &drv->states[index]; > > > unsigned long eax = flg2MWAIT(state->flags); > > > unsigned long ecx = 1; /* break on interrupt flag */ > > > - bool tick; > > > - > > > - if (!static_cpu_has(X86_FEATURE_ARAT)) { > > > - /* > > > - * Switch over to one-shot tick broadcast if the target C-state > > > - * is deeper than C1. > > > - */ > > > - if ((eax >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) { > > > - tick = true; > > > - tick_broadcast_enter(); > > > - } else { > > > - tick = false; > > > - } > > > - } > > > > > > mwait_idle_with_hints(eax, ecx); > > > > > > - if (!static_cpu_has(X86_FEATURE_ARAT) && tick) > > > - tick_broadcast_exit(); > > > - > > > return index; > > > } > > > > > > @@ -1460,6 +1443,23 @@ static bool __init intel_idle_verify_cst > > > return true; > > > } > > > > > > +static bool __init intel_idle_state_needs_timer_stop(struct cpuidle_state *state) > > > +{ > > > + unsigned long eax = flg2MWAIT(state->flags); > > > + > > > + if (boot_cpu_has(X86_FEATURE_ARAT)) > > > + return false; > > > + > > > + /* > > > + * Switch over to one-shot tick broadcast if the target C-state > > > + * is deeper than C1. > > > + */ > > > + if ((eax >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) > > > + return true; > > > + > > > + return false; > > > +} > > > + > > > static void __init intel_idle_init_cstates_icpu(struct cpuidle_driver *drv) > > > { > > > int cstate; > > > @@ -1507,6 +1507,9 @@ static void __init intel_idle_init_cstat > > > !(cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_ALWAYS_ENABLE))) > > > drv->states[drv->state_count].flags |= CPUIDLE_FLAG_OFF; > > > > > > + if (intel_idle_state_needs_timer_stop(&drv->states[drv->state_count])) > > > + drv->states[drv->state_count].flags |= CPUIDLE_FLAG_TIMER_STOP; > > > + > > > drv->state_count++; > > > } > > > > This doesn't cover the ACPI case AFAICS. > > aa6b43d57f99 ("ACPI: processor: Use CPUIDLE_FLAG_TIMER_STOP") > > did that, no? Nope. intel_idle_init_cstates_acpi() needs to be updated too as it doesn't pick up the flags automatically. It looks like CPUIDLE_FLAG_RCU_IDLE needs to be copied too.