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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 A6624C31E40 for ; Fri, 9 Aug 2019 20:29:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 770FB214C6 for ; Fri, 9 Aug 2019 20:29:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="MLDFO4GF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729591AbfHIU31 (ORCPT ); Fri, 9 Aug 2019 16:29:27 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:39412 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729533AbfHIU3X (ORCPT ); Fri, 9 Aug 2019 16:29:23 -0400 Received: by mail-pl1-f195.google.com with SMTP id b7so45442325pls.6 for ; Fri, 09 Aug 2019 13:29:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=A9NhgTl7zfb3l1+NKbkDU/P+hrZFZUgJYh8JpIsec0E=; b=MLDFO4GFjW+A+4D9jAGcXTdfEyXRibjGCZMZZ5cEKAKSUpleSuAJgryFida0cokfZq oApVkJ/APJFAV//OVXvzZNrwYnSrC75TeDz0WS6iedhnobDKVsLxx9AjkKAH6+y+HyhV iubniIEPLSFYfria85M3qoMT6UyFfMsUqYawE= 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:user-agent; bh=A9NhgTl7zfb3l1+NKbkDU/P+hrZFZUgJYh8JpIsec0E=; b=RnonJfs2NZs4m4gg7Q7ckKhKDSr13VcKIwFz7UBpfn46e+lUNVlw5xIaFEp/2JkBUS 1n5b1zSK5QmVkDZrBfws0DlUBnxn84N55NcneaWNrhsXMEnDQn9BYUbfym4KG3+j/6dU 2V+hNIqInEME5ZzdIiRFLWHwSQQqfjMMqwoThPZaB5Db4Xh1YdptoStspiW2XqbuER7L tqQNTz3AZMyI9BSbyVZrL87pbHEx88Wka1B9UG5ftLfRl8fdfG0A63Yn5XRdIyGAyAQj OOk8xTGy2iIbuDtEtqEcHW1dHBym4h24rubqPLhGGjv3P2whqNIeRNQc8TDJtI09tmx4 dF7A== X-Gm-Message-State: APjAAAXFL2m1PlaV8C4YgrEIUZ7ihMyFz8+tZqtb7NnhW7JElpUu7q1a +hVEa2DADCJlb6NHAgQILI72Zw== X-Google-Smtp-Source: APXvYqxAzSoqBoiHk7b+bAdo2F3seV7zxBnNzc1weazPV3iVfTuGK1yaJE3TB+II7IRyJkDlx9xARQ== X-Received: by 2002:a17:902:ac88:: with SMTP id h8mr15447969plr.77.1565382562846; Fri, 09 Aug 2019 13:29:22 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id v185sm110394406pfb.14.2019.08.09.13.29.21 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 09 Aug 2019 13:29:21 -0700 (PDT) Date: Fri, 9 Aug 2019 16:29:20 -0400 From: Joel Fernandes To: "Paul E. McKenney" Cc: Byungchul Park , linux-kernel@vger.kernel.org, Rao Shoaib , max.byungchul.park@gmail.com, kernel-team@android.com, kernel-team@lge.com, Davidlohr Bueso , Josh Triplett , Lai Jiangshan , Mathieu Desnoyers , rcu@vger.kernel.org, Steven Rostedt Subject: Re: [PATCH RFC v1 1/2] rcu/tree: Add basic support for kfree_rcu batching Message-ID: <20190809202920.GE255533@google.com> References: <20190806235631.GU28441@linux.ibm.com> <20190807094504.GB169551@google.com> <20190807175215.GE28441@linux.ibm.com> <20190808095232.GA30401@X58A-UD3R> <20190808125607.GB261256@google.com> <20190808233014.GA184373@google.com> <20190809151619.GD28441@linux.ibm.com> <20190809153924.GB211412@google.com> <20190809163346.GF28441@linux.ibm.com> <20190809202226.GC255533@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190809202226.GC255533@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 09, 2019 at 04:22:26PM -0400, Joel Fernandes wrote: > > > > o With any of the above, invoke rcu_momentary_dyntick_idle() along > > > > with cond_resched() in your kfree_rcu() loop. This simulates > > > > a trip to userspace for nohz_full CPUs, so if this helps for > > > > non-nohz_full CPUs, adjustments to the kernel might be called for. > > I did not try this yet. But I am thinking why would this help in nohz_idle > case? In nohz_idle we already have the tick active when CPU is idle. I guess > it is because there may be a long time that elapses before > rcu_data.rcu_need_heavy_qs == true ? Sorry, here I meant 'tick active when CPU is not idle'. thanks, - Joel