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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 17F1BC433ED for ; Thu, 20 May 2021 22:34:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E6ADB613AD for ; Thu, 20 May 2021 22:34:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231640AbhETWgL (ORCPT ); Thu, 20 May 2021 18:36:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52944 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229951AbhETWgK (ORCPT ); Thu, 20 May 2021 18:36:10 -0400 Received: from mail-pg1-x530.google.com (mail-pg1-x530.google.com [IPv6:2607:f8b0:4864:20::530]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CE405C061574 for ; Thu, 20 May 2021 15:34:47 -0700 (PDT) Received: by mail-pg1-x530.google.com with SMTP id t30so12831701pgl.8 for ; Thu, 20 May 2021 15:34:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=bTS10J8Fh4/AouNMIjaBMXhuO+gGwEf47jXocC6JZwU=; b=Z5qQMq/4e1ey9FmErr3jqiPFdMJEGgWcJQcEzl82VmhbsDd0Tgy3HSm5aBoPa5DnBH 7bDqehGpiSCtOltIvKVIHWrvm10Q0y3PqL8J/ccnX4iSdALIzJJFjxyLY+pGZ8u0edwW RGzRhD+AA+bsexpUJ5MB69eRn9QEQkjDVYjRQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=bTS10J8Fh4/AouNMIjaBMXhuO+gGwEf47jXocC6JZwU=; b=Kt1WlW7AbXc1fTneok1GQ82SscaQ8ZX+r7Qtb0siyTmJ8ATLS/jXpXUmSUqKBY3+ya 03ROR1DqxpEl3tuCe45Y+rwiqJO+vlhFTgsU+SowK3ePdHqumkiHX0b0HHxShSveoqxG WD9ni1lM58tP85d5OtEk2FjXzdv6P1LUHeEPxSQmZyjBypiHMhqqQKq/5Shgxo0DRuU/ RbF1vozi3kevDDelYVkUhftJjx7BARArpP47niVz6jvdz6ZBLgVEedi/Bont2w+S9t07 kwqPWLxWXl5dLLlHfVp4rP+thYsHrIC4DNxf4/GydM3BIkEHJGe13VWI4RMl+D42WzR/ ZtWA== X-Gm-Message-State: AOAM531KWofk5n6gU4IoErGxEK9q8/3D7o5dnBBnRImR1zQH+FV5L2Jw upBTbh0Drg/ycXdeQMv7XYozyXTRH8V4bA== X-Google-Smtp-Source: ABdhPJySvh04MDIPE23NVRcL5tmdYVXsmdK3rbDvUka+pcsQ57zAzLVvWxIh9RNuz/OKLm+tiNFs3A== X-Received: by 2002:a63:5a01:: with SMTP id o1mr3705692pgb.313.1621550087293; Thu, 20 May 2021 15:34:47 -0700 (PDT) Received: from google.com ([2409:10:2e40:5100:245d:3890:fa95:996e]) by smtp.gmail.com with ESMTPSA id 4sm2850883pgn.31.2021.05.20.15.34.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 May 2021 15:34:46 -0700 (PDT) Date: Fri, 21 May 2021 07:34:41 +0900 From: Sergey Senozhatsky To: "Paul E. McKenney" Cc: Sergey Senozhatsky , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , Suleiman Souhlal , rcu@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] rcu/tree: consider time a VM was suspended Message-ID: References: <20210516102716.689596-1-senozhatsky@chromium.org> <20210517162312.GG4441@paulmck-ThinkPad-P17-Gen-1> <20210518231514.GS4441@paulmck-ThinkPad-P17-Gen-1> <20210520145708.GK4441@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210520145708.GK4441@paulmck-ThinkPad-P17-Gen-1> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (21/05/20 07:57), Paul E. McKenney wrote: > > > > Sounds good. I can cook a patch and run some tests. > > Or do you want to send a patch? > > Given that you have the test setup, things might go faster if you do > the patch, especially taking timezones into consideration. Of course, > if you run into difficulties, you know where to find me. OK. Sounds good to me. > > While VCPU-2 has PVCLOCK_GUEST_STOPPED set (resuming) and is in > > check_cpu_stall(), the VCPU-3 is executing: > > > > apic_timer_interrupt() > > tick_irq_enter() > > tick_do_update_jiffies64() > > do_timer() > > OK, but the normal grace period time is way less than one second, and > the stall timeout in mainline is 21 seconds, so that would be a -lot- > of jiffies of skew. Or does the restarting really take that long a time? That's a good question. I see huge jiffies spike in the logs. I suspect that resuming a VM can take some time, especially on a "not powerful at all" overcommitted host (more virtual CPUs than physical ones).