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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B704BC25B08 for ; Thu, 11 Aug 2022 02:32:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233799AbiHKCcE (ORCPT ); Wed, 10 Aug 2022 22:32:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233635AbiHKCcB (ORCPT ); Wed, 10 Aug 2022 22:32:01 -0400 Received: from mail-qv1-xf34.google.com (mail-qv1-xf34.google.com [IPv6:2607:f8b0:4864:20::f34]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7668388DE0 for ; Wed, 10 Aug 2022 19:32:00 -0700 (PDT) Received: by mail-qv1-xf34.google.com with SMTP id i4so12406895qvv.7 for ; Wed, 10 Aug 2022 19:32:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=content-transfer-encoding:in-reply-to:references:cc:to:from :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc; bh=59BW7/Ip/IlB4q8qRutBL8VhwSHLJCviZn8DE3Eq3+M=; b=g6Hrbi1SrgMQgfXV0cFES51r8PcZl3OXbTHxf6RmislSBdOpCuv3kcNzTTj1qmPPmA ZXM1Z6gib8ZDe8O9XcZrzXqhvxdfngB9TupfB5R1oVHUXeGScY2ZnPghgAWfFaPeGu6e atrhvF5e5/ByNWnbYZtWLOKzdieVRgw+1UWik= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:references:cc:to:from :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc; bh=59BW7/Ip/IlB4q8qRutBL8VhwSHLJCviZn8DE3Eq3+M=; b=cSvgnMZ5cJiE3ip7h6W3iKST8WMkrJSA+mDYl7y+YBi/h/+3qZKFYahTVHAWwrDlbB wum9mzHZY/FfWW5nDIkZFVknyONjAbj5Bvt3AeIIAxDR2hkUahzo0p8HOYuLr/ZZH9RV yBWplb+xx5Gpd0K7H51XOlK0Fxs78UDRI/g48oLCq4v3bbhTiBNAev9PyuV5bnqBYEzh L9R/PRnSgcVQfgA47mNS3o2wznaSFN0NSEWJ01QYvg1y2yDyflrAQ+MMG8UdA4z5u5Cu 42bhb6cgIyB1B7zFtNfc0HEBuMC2RXNENOiJdJ8t7uIbPxPTmpWzsAGXd5m9cwvuCDMc uC3g== X-Gm-Message-State: ACgBeo0ZKVyWNehJHEJBko/7HjKdXH8CJUiyMuYWaafRQaJtfiIS7nJY VUle3IqeaPg0wjmuMxJO60ZZm4I4r6a9aw== X-Google-Smtp-Source: AA6agR5Qjb7gj8xWC6fpxPO5IpeCozRPpLsy6DnI8vYWq60hc05soAvHdRaJRnisycVD9fXU/ImYKA== X-Received: by 2002:a05:6214:a4f:b0:474:8b63:556f with SMTP id ee15-20020a0562140a4f00b004748b63556fmr26454295qvb.55.1660185119339; Wed, 10 Aug 2022 19:31:59 -0700 (PDT) Received: from [10.0.0.40] (c-73-148-104-166.hsd1.va.comcast.net. [73.148.104.166]) by smtp.gmail.com with ESMTPSA id t11-20020a05622a01cb00b0033c36ef019esm1038212qtw.63.2022.08.10.19.31.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 10 Aug 2022 19:31:58 -0700 (PDT) Message-ID: <87663566-ed67-fee8-4598-13591f2f072b@joelfernandes.org> Date: Wed, 10 Aug 2022 22:31:56 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.0.2 Subject: Re: [PATCH v3 resend 0/6] Implement call_rcu_lazy() and miscellaneous fixes Content-Language: en-US From: Joel Fernandes To: linux-kernel@vger.kernel.org Cc: rushikesh.s.kadam@intel.com, urezki@gmail.com, neeraj.iitr10@gmail.com, frederic@kernel.org, paulmck@kernel.org, rostedt@goodmis.org, rcu@vger.kernel.org References: <20220809034517.3867176-1-joel@joelfernandes.org> <308db02b-b56d-2df1-ee33-7f66e6a85f63@joelfernandes.org> In-Reply-To: <308db02b-b56d-2df1-ee33-7f66e6a85f63@joelfernandes.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/10/2022 10:23 PM, Joel Fernandes wrote: > > > On 8/8/2022 11:45 PM, Joel Fernandes (Google) wrote: >> Just a refresh of v3 with one additional debug patch. v3's cover letter is here: >> https://lore.kernel.org/all/20220713213237.1596225-1-joel@joelfernandes.org/ >> >> I just started working on this again while I have some time during paternity >> leave ;-) So I thought I'll just send it out again. No other changes other >> than that 1 debug patch I added on the top. >> >> Next I am going to go refine the power results as mentioned in Paul's comments >> on the last cover letter. > > Side note: Here is another big selling point for call_rcu_lazy(). > Instead of _lazy(), if you just increased jiffies_till_first_fqs, and > slowed *all* call_rcu() down to achieve the same effect, that would > affect percpu refcounters switching to atomic-mode, for example. > > They switch to atomic mode by calling __percpu_ref_switch_mode() which > is called by percpu_ref_switch_to_atomic_sync().> > This will slow this call down for the full lazy duration which will slow > down suspend in blk_pre_runtime_suspend(). Correction while I am going on the record (got to be careful these days). It *might* slow down RCU for the full lazy duration, unless of course a fly-by rescue call_rcu() comes in. - Joel