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Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qibWc-00DegS-0S; Tue, 19 Sep 2023 14:16:27 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 3C68C300585; Tue, 19 Sep 2023 16:16:27 +0200 (CEST) Date: Tue, 19 Sep 2023 16:16:27 +0200 From: Peter Zijlstra To: John Paul Adrian Glaubitz Cc: Matthew Wilcox , Thomas Gleixner , Linus Torvalds , Ankur Arora , linux-kernel@vger.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, mgorman@suse.de, rostedt@goodmis.org, 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, Geert Uytterhoeven , linux-m68k@lists.linux-m68k.org, Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Brian Cain , linux-hexagon@vger.kernel.org, Richard Henderson , Ivan Kokshaysky , Matt Turner , linux-alpha@vger.kernel.org Subject: Re: Arches that don't support PREEMPT Message-ID: <20230919141627.GB39281@noisy.programming.kicks-ass.net> References: <20230911150410.GC9098@noisy.programming.kicks-ass.net> <87h6o01w1a.fsf@oracle.com> <20230912082606.GB35261@noisy.programming.kicks-ass.net> <87cyyfxd4k.ffs@tglx> <87led2wdj0.ffs@tglx> <0e69f7df80dc5878071deb0d80938138d19de1d1.camel@physik.fu-berlin.de> <20230919134218.GA39281@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 9C5454001E X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: ssoex3hms8wkos99t5uy6yzqxnda43i4 X-HE-Tag: 1695133011-794829 X-HE-Meta: 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 3T9P0jmu 6fEuzT6vjjtw20Bp57KQfbmEOxXJSWEvrxqXkQuG6mpUiWE5D0x+JIPUDnMVvXponAdd3iSa4he+/AZNIc/w3lBG0kN0dQUotzCnEC2eqRoVi1sSc82qTxJkO1I+8ykbczj4/QBEo9CpcPw8= 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: On Tue, Sep 19, 2023 at 03:48:09PM +0200, John Paul Adrian Glaubitz wrote: > On Tue, 2023-09-19 at 15:42 +0200, Peter Zijlstra wrote: > > > The agreement to kill off ia64 wasn't an invitation to kill off other stuff > > > that people are still working on! Can we please not do this? > > > > If you're working on one of them, then surely it's a simple matter of > > working on adding CONFIG_PREEMPT support :-) > > As Geert poined out, I'm not seeing anything particular problematic with the > architectures lacking CONFIG_PREEMPT at the moment. This seems to be more > something about organizing KConfig files. The plan in the parent thread is to remove PREEMPT_NONE and PREEMPT_VOLUNTARY and only keep PREEMPT_FULL. > I find it a bit unfair that maintainers of architectures that have huge companies > behind them use their manpower to urge less popular architectures for removal just > because they don't have 150 people working on the port so they can keep up with > design changes quickly. PREEMPT isn't something new. Also, I don't think the arch part for actually supporting it is particularly hard, mostly it is sticking the preempt_schedule_irq() call in return from interrupt code path. If you convert the arch to generic-entry (a much larger undertaking) then you get this for free.