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[209.85.208.51]) by smtp.gmail.com with ESMTPSA id da23-20020a056402177700b005312a2b00cbsm2611908edb.63.2023.09.19.11.52.39 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 Sep 2023 11:52:39 -0700 (PDT) Received: by mail-ed1-f51.google.com with SMTP id 4fb4d7f45d1cf-52bd9ddb741so7623899a12.0 for ; Tue, 19 Sep 2023 11:52:39 -0700 (PDT) X-Received: by 2002:a50:fc0e:0:b0:532:e71b:5ead with SMTP id i14-20020a50fc0e000000b00532e71b5eadmr258934edr.32.1695149559235; Tue, 19 Sep 2023 11:52:39 -0700 (PDT) MIME-Version: 1.0 References: <87zg1u1h5t.fsf@oracle.com> <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> <87pm2eui95.ffs@tglx> <20230919143816.1741760a@gandalf.local.home> In-Reply-To: <20230919143816.1741760a@gandalf.local.home> From: Linus Torvalds Date: Tue, 19 Sep 2023 11:52:22 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: Arches that don't support PREEMPT To: Steven Rostedt Cc: Thomas Gleixner , John Paul Adrian Glaubitz , Peter Zijlstra , Matthew Wilcox , 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, 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 Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 4AE8C120015 X-Stat-Signature: 7fc94czms5816i6pbhig9kwesbcqr9mj X-HE-Tag: 1695149562-904430 X-HE-Meta: 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 rYGN+zCY 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 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, 19 Sept 2023 at 11:37, Steven Rostedt wrote: > > We could simply leave the cond_resched() around but defined as nops for > everything but the "nostalgia club" to keep them from having any regressions. I doubt the nostalgia club cares about some latencies (that are usually only noticeable under extreme loads anyway). And if they do, maybe that would make somebody sit down and look into doing it right. So I think keeping it around would actually be both useless and counter-productive. Linus