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Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1r0hU9-000vU8-0w; Wed, 08 Nov 2023 12:16:41 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 5E172300585; Wed, 8 Nov 2023 13:16:41 +0100 (CET) Date: Wed, 8 Nov 2023 13:16:41 +0100 From: Peter Zijlstra To: Ankur Arora Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, 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, rostedt@goodmis.org, David.Laight@aculab.com, richard@nod.at, mjguzik@gmail.com Subject: Re: [RFC PATCH 00/86] Make the kernel preemptible Message-ID: <20231108121641.GC4779@noisy.programming.kicks-ass.net> References: <20231107215742.363031-1-ankur.a.arora@oracle.com> <20231108085156.GD8262@noisy.programming.kicks-ass.net> <87bkc4lfxp.fsf@oracle.com> <20231108101330.GK3818@noisy.programming.kicks-ass.net> <87leb8ik6b.fsf@oracle.com> <20231108111415.GP8262@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231108111415.GP8262@noisy.programming.kicks-ass.net> X-Rspamd-Queue-Id: 6D64510000B X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: bcxgmi1eqegb97y1wjurd5rnme3ehryq X-HE-Tag: 1699445833-261385 X-HE-Meta: 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 MZqODOGk dCQd09VG+EgfvJ5wvJfDRwZ4fOnCaurtK0PBwxj2oMO3xATd0rBvJfcOHMA2KQVRulkQQFHFyC3AzS4LdDeNnpNuep7MF1dFTeDvwV0hHXdy3HA5RPm2p44GXR2uzC8vf49BHoeilCeq1McE= 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 Wed, Nov 08, 2023 at 12:14:15PM +0100, Peter Zijlstra wrote: > I would really suggest you start with transforming VOLUNTARY into the > LAZY thing, keep it as simple and narrow as possible. Possibly make it worse first, add LAZY as a fourth option, then show it makes VOLUNTARY redundant, kill that. > Once you've got that done, then you can try and argue that NONE makes no > sense and try and take it out. This also pushes out having to deal with the !PREEMPT archs until the very last moment. And once you're here, cond_resched() should be an obvious no-op function and you can go delete them. Anyway, as said, smaller steps more better. Nobody likes 86 patches in their inbox in the morning (or at any time really).