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 BC0B2C4332F for ; Wed, 8 Nov 2023 00:00:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231316AbjKHAAV (ORCPT ); Tue, 7 Nov 2023 19:00:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229844AbjKHAAT (ORCPT ); Tue, 7 Nov 2023 19:00:19 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7BE96184 for ; Tue, 7 Nov 2023 16:00:17 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6A48CC433C8; Wed, 8 Nov 2023 00:00:13 +0000 (UTC) Date: Tue, 7 Nov 2023 19:00:16 -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 Subject: Re: [RFC PATCH 00/86] Make the kernel preemptible Message-ID: <20231107190016.2da8c402@gandalf.local.home> In-Reply-To: <877cmtxh77.fsf@oracle.com> References: <20231107215742.363031-1-ankur.a.arora@oracle.com> <20231107180153.4a02d2ba@gandalf.local.home> <877cmtxh77.fsf@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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 07 Nov 2023 15:43:40 -0800 Ankur Arora wrote: > > The TIF_NEED_RESCHED flag is evaluated at all three of the preemption > points. TIF_NEED_RESCHED_LAZY only needs to be evaluated at ret-to-user. > > ret-to-user ret-to-kernel preempt_count() > NEED_RESCHED_LAZY Y N N > NEED_RESCHED Y Y Y > > Based on how various preemption models set the flag they would cause > preemption at: I would change the above to say "set the NEED_SCHED flag", as "set the flag" is still ambiguous. Or am I still misunderstanding the below table? > > ret-to-user ret-to-kernel preempt_count() > none Y N N > voluntary Y Y Y > full Y Y Y > -- Steve