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Tue, 25 Feb 2025 15:10:18 -0800 (PST) Date: Tue, 25 Feb 2025 23:10:14 +0000 From: Qais Yousef To: Chen Yu Cc: Peter Zijlstra , zihan zhou <15645113830zzh@gmail.com>, oe-lkp@lists.linux.dev, kernel test robot , lkp@intel.com, linux-kernel@vger.kernel.org, x86@kernel.org, Vincent Guittot , aubrey.li@linux.intel.com, yu.c.chen@intel.com Subject: Re: [tip:sched/core] [sched] 2ae891b826: hackbench.throughput 6.2% regression Message-ID: <20250225231014.yztrap5ihain3cd2@airbuntu> References: <202502251026.bb927780-lkp@intel.com> <20250225122705.GD34233@noisy.programming.kicks-ass.net> <20250225134220.qjctfqwwhjz7bspp@airbuntu> 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=utf-8 Content-Disposition: inline In-Reply-To: On 02/25/25 23:35, Chen Yu wrote: > On 2025-02-25 at 13:42:20 +0000, Qais Yousef wrote: > > On 02/25/25 21:15, Chen Yu wrote: > > > On 2025-02-25 at 13:27:05 +0100, Peter Zijlstra wrote: > > > > On Tue, Feb 25, 2025 at 05:31:34PM +0800, Chen Yu wrote: > > > > > > > > > > > > > > But consider that the 6% regression is not that high, and the user might customize > > > > > base_slice via debugfs on-demand, we can keep an eye on this and revist it in the > > > > > future(we have encountered some SPECjbb regression due to over-preemption). > > > > > > > > You can specify a per-task slice using sched_attr::sched_runtime. Also > > > > see commit 857b158dc5e8 ("sched/eevdf: Use sched_attr::sched_runtime to > > > > set request/slice suggestion") > > > > > > > > > > > > > > Thanks, we'll have a try during the next test cycle. > > > > Could you also try with HRTICK enabled? > > > > echo HRTICK | sudo tee /sys/kernel/debug/sched/features > > Sure. Is HRTICK supposed to encourage preemption? I thought > hackbench might be sensitive to preemption(downgrading). Yes my bad, I don't know why I read this as preemption was happening later not earlier. Please ignore me then. Thanks -- Qais Yousef