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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 69401C2B9F4 for ; Sat, 19 Jun 2021 08:02:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3E687611B0 for ; Sat, 19 Jun 2021 08:02:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233143AbhFSIEp (ORCPT ); Sat, 19 Jun 2021 04:04:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229466AbhFSIEo (ORCPT ); Sat, 19 Jun 2021 04:04:44 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E9041C061574 for ; Sat, 19 Jun 2021 01:02:33 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1624089751; 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=ZWvtqV3TeC0Tm9I9yeacEOChKZjCO9EBxWKvJ6avhNw=; b=WN+yU7SZfehMCpp5CyrAKTgEbZFRLGsjXfQxUkoAWyInqm8DsQeQC3MJN4gp55taVfAGfD /ligzhR/EAcTO/c2XIPhOBptyhO2BuP7vciH8pZi+c3rITz3VqLWJ5+Up3l/+qmX1+kmMt 7KZ5kJqmOeVOlMFl0Dm9KteOkfiSkbYPlJbklD29gq5JBr5Z66t06WP763Lyw53kTfG7eZ TW6lhAY2Ww8p5g6I+u460VQjXpUyImf88ZQAKkXnH+28P+DoRE4U8ruDWCI7qjbx67+CuN Pw1/NKIG7PaiqdE7+eaQbmt258y/rHM2IJ9aHFpmSy/4XoLFt+oIQYM+LWSF/g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1624089751; 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=ZWvtqV3TeC0Tm9I9yeacEOChKZjCO9EBxWKvJ6avhNw=; b=WiVq9cJx5k1pZtlSGE6et5TvC+8fnv6Midr36zeiiKVwvhBDR1JF1LMHA209djPQ6B6m+2 gbaiYj3m29HHyEBg== To: Ani Sinha , linux-kernel@vger.kernel.org Cc: anirban.sinha@nokia.com, Ani Sinha , Frederic Weisbecker , Ingo Molnar Subject: Re: [PATCH] Add missing kernel log when enabling NO_HZ_FULL is not possible In-Reply-To: <20210611103937.827565-1-ani@anisinha.ca> References: <20210611103937.827565-1-ani@anisinha.ca> Date: Sat, 19 Jun 2021 10:02:30 +0200 Message-ID: <878s36e0yx.ffs@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ani, On Fri, Jun 11 2021 at 16:09, Ani Sinha wrote: > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index 828b091501ca..a82480c036e2 100644 > --- a/kernel/time/tick-sched.c > +++ b/kernel/time/tick-sched.c > @@ -937,10 +937,18 @@ static void tick_nohz_full_update_tick(struct tick_sched *ts) > if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE) > return; > > - if (can_stop_full_tick(cpu, ts)) > + if (can_stop_full_tick(cpu, ts)) { > tick_nohz_stop_sched_tick(ts, cpu); > - else if (ts->tick_stopped) > - tick_nohz_restart_sched_tick(ts, ktime_get()); > + } else { > + /* > + * Don't allow the user to think they can get > + * full NO_HZ with this machine. > + */ > + WARN_ONCE(tick_nohz_full_running, > + "NO_HZ_FULL will not work with current sched clock"); How is that warning useful and even remotely correct? can_stop_full_tick() has 4 x 5 == 20 ways to return false and the smaller portion of them is related to sched clock. Thanks, tglx