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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38f259f771dsm10130003f8f.81.2025.02.16.11.05.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 16 Feb 2025 11:05:41 -0800 (PST) Date: Sun, 16 Feb 2025 19:05:40 +0000 From: David Laight To: Qais Yousef Cc: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Vincent Guittot , Juri Lelli , Steven Rostedt , John Stultz , Saravana Kannan , Dietmar Eggemann , Frederic Weisbecker , linux-kernel@vger.kernel.org Subject: Re: [PATCH] Kconfig.hz: Change default HZ to 1000 Message-ID: <20250216190540.254512a5@pumpkin> In-Reply-To: <20250210001915.123424-1-qyousef@layalina.io> References: <20250210001915.123424-1-qyousef@layalina.io> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 10 Feb 2025 00:19:15 +0000 Qais Yousef wrote: > The frequency at which TICK happens is very important from scheduler > perspective. There's a responsiveness trade-of that for interactive > systems the current default is set too low. The problem I see is that most people use a kernel from one of the distributions. So you need to persuade them to change their default. Change the default 'default' won't necessarily have any effect. OTOH if you decouple the timer interrupt rate from HZ (or jiffies) then it becomes possible to boot time (or even run-time) change the timer interrupt rate. So it makes much more sense to fix 'jiffies' as a 1ms counter and then configure the timer interrupt to be a number of ms/jiffies. This would be similar all the simplifications that came about by making the high precision timestamps (etc) ns regardless of the actual resolution on any specific hardware. David