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 CAC9BC54EE9 for ; Wed, 7 Sep 2022 09:56:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230124AbiIGJ4O (ORCPT ); Wed, 7 Sep 2022 05:56:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52496 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230089AbiIGJ4M (ORCPT ); Wed, 7 Sep 2022 05:56:12 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 30B222A436; Wed, 7 Sep 2022 02:56:05 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E4CF861834; Wed, 7 Sep 2022 09:56:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD67DC433D7; Wed, 7 Sep 2022 09:56:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662544564; bh=43j1/GXOQ8HjrTpBSPu9G1AgM4IhX1nLYs/I4J5dp1g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kWpHwkKnG5jm3GRd1QEOnAGFiOkgolGgxZJrrbVgaR804F1WxHy9qM5tspu2/J9Ic 6vGLAf1Ke5HOFhysEIRWwnDMfwEQ73a6939yBVKcICL4nJS0bXZFgbMJG810UXtPs3 YQ/nUIG3ZX1C/DxIQ/QO4PkcrRpTPG5BVrByiVCg1JIaXuSdInQ8fmW3tsF3jw6Vu/ pgoEOCbU0PHBwVJwQkBeuwf7SiwtMTC/ManazRJbd52XMe/A9PCXMtA4IUFsqiYVsA Dl3VI+KjU6IEhuCo5JbhWw16+DEp3+ObqcfsJ6xy9t9GLfVGa9WhwMy7YdTLZR15kX GCw2JM6mbblgQ== Date: Wed, 7 Sep 2022 11:56:01 +0200 From: Frederic Weisbecker To: Joel Fernandes Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org, rushikesh.s.kadam@intel.com, urezki@gmail.com, neeraj.iitr10@gmail.com, paulmck@kernel.org, rostedt@goodmis.org, vineeth@bitbyteword.org, boqun.feng@gmail.com Subject: Re: [PATCH v5 06/18] rcu: Introduce call_rcu_lazy() API implementation Message-ID: <20220907095601.GA194889@lothringen> References: <20220901221720.1105021-7-joel@joelfernandes.org> <20220902152132.GA115525@lothringen> <20220906151757.GA183806@lothringen> <64f5770c-df37-8975-200d-7908de23fa73@joelfernandes.org> <4f6061f0-0de7-2916-dc6e-9f5af9b944c0@joelfernandes.org> <20220906191110.GA187950@lothringen> <8812ea75-ef14-0d5d-19d8-bda70394b41a@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8812ea75-ef14-0d5d-19d8-bda70394b41a@joelfernandes.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 06, 2022 at 10:56:01PM -0400, Joel Fernandes wrote: > On the issue of regressions with non-lazy things being treated as lazy, I was > thinking of adding a bounded-time-check to: > > [PATCH v5 08/18] rcu: Add per-CB tracing for queuing, flush and invocation. > > Where, if a non-lazy CB takes an abnormally long time to execute (say it was > subject to a race-condition), it would splat. This can be done because I am > tracking the queue-time in the rcu_head in that patch. > > On another note, boot time regressions show up pretty quickly (at least on > ChromeOS) when non-lazy things become lazy and so far with the latest code it > has fortunately been pretty well behaved. Makes sense. We definetly need some sort of detection for delayed non-lazy callbacks. Thanks! > > Thanks, > > - Joel