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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 29FFDC388F9 for ; Mon, 23 Nov 2020 22:37:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D5055206E3 for ; Mon, 23 Nov 2020 22:37:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="aMJVTnpe"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="/IgFnC1c" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732668AbgKWWgl (ORCPT ); Mon, 23 Nov 2020 17:36:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36944 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732465AbgKWWgk (ORCPT ); Mon, 23 Nov 2020 17:36:40 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 741E2C0613CF; Mon, 23 Nov 2020 14:36:40 -0800 (PST) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1606170998; 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=WvO23hlLALMng1Q2U21zDAYNIYaryK/sfsJBDYAr09U=; b=aMJVTnpeicogkyC/efGjwmX3nDfxPzpU0yCeoeIXHk9+7UoQZhyi3LZ1qE6GkqM7AgAu3T Y1mkgrSzYA2PnBKQNVznhEXV1zhNYvUe1wIOr6yDuSn13/1pc47a9EdHA2t7nijPL/sKKK lK+UkhP7DbZ5FK31B2hEqLh+1kwi1cC1x7JkKNQN8JzVjYjdH3VZ0hJOQ1nsa/4jPuCUj1 tRT8DT2YApICqrLqMwM1Sp31fNVdMdm3/DZVw6ACsAHuIliXJm+ILgysM3QUscdBfPRjjX Y+68U89FN8uLHmnO4gOlFpDYp0rN4mRDF45xLqM8g1ioq7HahQkis+gfWtWMTg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1606170998; 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=WvO23hlLALMng1Q2U21zDAYNIYaryK/sfsJBDYAr09U=; b=/IgFnC1c+C9OlSoASnKFI4bLxgSx6hMe7jg1jeftA5FJxxiWPEQqQmaHRi7vhLQlahgiS9 X6tngBQMHZOaXNAQ== To: Alex Belits , "nitesh\@redhat.com" , "frederic\@kernel.org" Cc: Prasun Kapoor , "linux-api\@vger.kernel.org" , "davem\@davemloft.net" , "trix\@redhat.com" , "mingo\@kernel.org" , "catalin.marinas\@arm.com" , "rostedt\@goodmis.org" , "linux-kernel\@vger.kernel.org" , "peterx\@redhat.com" , "linux-arch\@vger.kernel.org" , "mtosatti\@redhat.com" , "will\@kernel.org" , "peterz\@infradead.org" , "leon\@sidebranch.com" , "linux-arm-kernel\@lists.infradead.org" , "pauld\@redhat.com" , "netdev\@vger.kernel.org" Subject: Re: [PATCH v5 7/9] task_isolation: don't interrupt CPUs with tick_nohz_full_kick_cpu() In-Reply-To: <76ed0b222d2f16fb5aebd144ac0222a7f3b87fa1.camel@marvell.com> References: <8d887e59ca713726f4fcb25a316e1e932b02823e.camel@marvell.com> <76ed0b222d2f16fb5aebd144ac0222a7f3b87fa1.camel@marvell.com> Date: Mon, 23 Nov 2020 23:36:37 +0100 Message-ID: <87360zn1je.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 23 2020 at 17:58, Alex Belits wrote: > From: Yuri Norov > > For nohz_full CPUs the desirable behavior is to receive interrupts > generated by tick_nohz_full_kick_cpu(). But for hard isolation it's > obviously not desirable because it breaks isolation. > > This patch adds check for it. git grep 'This patch' Documentation/process/ > */ > void tick_nohz_full_kick_cpu(int cpu) > { > - if (!tick_nohz_full_cpu(cpu)) > + smp_rmb(); Undocumented smp_rmb() ... > + if (!tick_nohz_full_cpu(cpu) || task_isolation_on_cpu(cpu)) > return; I still have to see a convincing argument why task isolation is special and not just a straight forward extension of NOHZ full cpu isolation. It's not special as much as you want it to be special. Thanks, tglx