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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 865E6C4332F for ; Wed, 8 Nov 2023 00:27:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E17458000F; Tue, 7 Nov 2023 19:27:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DC79F8000D; Tue, 7 Nov 2023 19:27:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CB5EE8000F; Tue, 7 Nov 2023 19:27:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id BC48E8000D for ; Tue, 7 Nov 2023 19:27:09 -0500 (EST) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 910E21A0B68 for ; Wed, 8 Nov 2023 00:27:09 +0000 (UTC) X-FDA: 81432897378.25.290C97B Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf26.hostedemail.com (Postfix) with ESMTP id D7410140025 for ; Wed, 8 Nov 2023 00:27:07 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=none; spf=pass (imf26.hostedemail.com: domain of "SRS0=kuE6=GV=goodmis.org=rostedt@kernel.org" designates 145.40.68.75 as permitted sender) smtp.mailfrom="SRS0=kuE6=GV=goodmis.org=rostedt@kernel.org"; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1699403228; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vQKD6v6hC1dpxKSybyewNus4Rk7loTsshl2pXGQbVxs=; b=GsMzdSaxTUI4M3I/ofXjs+QHSLI2hindyD6nRwozaIPhIryJW+5q7pERhEoicrI585g8lt /rJYUF6zF4LHdoH18hYv5MMELcgodcCZ6Uqk4fEm4zddgVOHcasgBxYGTrz7YtjwcIHDy8 mllh4TQipiTwpDbN0hUf+ya0NnPtbCw= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1699403228; a=rsa-sha256; cv=none; b=yS6BG7CMJuLC9nNnoG155ZO/Gf6veyaMwvkNL+vevKexBnN2TAX2mspNcJO8+cwEfVsqqQ GhXOpPGzEwe+XFhEsG84XnX2Wy0x6JTYXYobXZruGj1U65BVmzVLlXChgJU/6sYLpYtGHj cWb5MoxvHczVjgKrh79Sm7kryUPObUc= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=none; spf=pass (imf26.hostedemail.com: domain of "SRS0=kuE6=GV=goodmis.org=rostedt@kernel.org" designates 145.40.68.75 as permitted sender) smtp.mailfrom="SRS0=kuE6=GV=goodmis.org=rostedt@kernel.org"; dmarc=none Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by ams.source.kernel.org (Postfix) with ESMTP id 41FACB816CB; Wed, 8 Nov 2023 00:27:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4659C433C8; Wed, 8 Nov 2023 00:27:00 +0000 (UTC) Date: Tue, 7 Nov 2023 19:27:03 -0500 From: Steven Rostedt To: Ankur Arora Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, peterz@infradead.org, torvalds@linux-foundation.org, paulmck@kernel.org, linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org, luto@kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, willy@infradead.org, mgorman@suse.de, jon.grimm@amd.com, bharata@amd.com, raghavendra.kt@amd.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, jgross@suse.com, andrew.cooper3@citrix.com, mingo@kernel.org, bristot@kernel.org, mathieu.desnoyers@efficios.com, geert@linux-m68k.org, glaubitz@physik.fu-berlin.de, anton.ivanov@cambridgegreys.com, mattst88@gmail.com, krypton@ulrich-teichert.org, David.Laight@ACULAB.COM, richard@nod.at, mjguzik@gmail.com, Simon Horman , Julian Anastasov , Alexei Starovoitov , Daniel Borkmann Subject: Re: [RFC PATCH 47/86] rcu: select PREEMPT_RCU if PREEMPT Message-ID: <20231107192703.1c493431@gandalf.local.home> In-Reply-To: <20231107215742.363031-48-ankur.a.arora@oracle.com> References: <20231107215742.363031-1-ankur.a.arora@oracle.com> <20231107215742.363031-48-ankur.a.arora@oracle.com> X-Mailer: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: D7410140025 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: hapdjho7sqt3p89orqmyfogkpwdd8139 X-HE-Tag: 1699403227-59366 X-HE-Meta: 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 2/NNxMeT j2E5T4F+f9EUvrp0AgYGlDSLaAhhEyH7DxkXtNIrkDuJmGrcd7+P1Y1gZRqPgLqYNXnt3QWJLMzrBEhN+YOATn1NHCmNf600kP4pnCgMC7/nSh+xtBEBrhfzpFPZuXZL5ERGEmWMgrVC1gvCd3ENH0y2C3JLtFM7zC6RJLwkEJle1NCFYacHp81zqN+gW+WMnBxr0SwVsbGsZ0ozV9+bwWMrjzdAoEpZzF57cjKguWbt1/nM5KZ3d2AafyHDdgu6+D9qfDFFTHE9pmaKLamk0RMyV2CLB3AWkdr0YRZlRhfgCaDSgbdUA220LPGvU8n6GxS6h X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 7 Nov 2023 13:57:33 -0800 Ankur Arora wrote: > With PREEMPTION being always-on, some configurations might prefer > the stronger forward-progress guarantees provided by PREEMPT_RCU=n > as compared to PREEMPT_RCU=y. > > So, select PREEMPT_RCU=n for PREEMPT_VOLUNTARY and PREEMPT_NONE and > enabling PREEMPT_RCU=y for PREEMPT or PREEMPT_RT. > > Note that the preemption model can be changed at runtime (modulo > configurations with ARCH_NO_PREEMPT), but the RCU configuration > is statically compiled. I wonder if we should make this a separate patch, and allow PREEMPT_RCU=n when PREEMPT=y? This could allow us to test this without this having to be part of this series. -- Steve