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Wed, 30 Jul 2025 02:46:28 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFKkBPIcxvn3I2VLjanO8enRfr0E8zNPS46Uf7PRzUN7RGEKOsEdB7MUQb6QgWZ0jBstua6bA== X-Received: by 2002:a05:6000:41d3:b0:3b7:974d:5359 with SMTP id ffacd0b85a97d-3b7974d597dmr873853f8f.32.1753868787970; Wed, 30 Jul 2025 02:46:27 -0700 (PDT) Received: from jlelli-thinkpadt14gen4.remote.csb ([151.43.90.121]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b785258135sm11317502f8f.42.2025.07.30.02.46.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Jul 2025 02:46:27 -0700 (PDT) Date: Wed, 30 Jul 2025 11:46:23 +0200 From: Juri Lelli To: Geert Uytterhoeven Cc: Peter Zijlstra , mingo@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, clm@meta.com, linux-kernel@vger.kernel.org, linux-m68k Subject: Re: [PATCH v2 02/12] sched/deadline: Less agressive dl_server handling Message-ID: References: <20250702114924.091581796@infradead.org> <20250702121158.465086194@infradead.org> 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-Disposition: inline In-Reply-To: Hello, On 30/07/25 11:34, Geert Uytterhoeven wrote: > Hi Peter, Apologies for interjecting. > On Wed, 2 Jul 2025 at 14:19, Peter Zijlstra wrote: > > Chris reported that commit 5f6bd380c7bd ("sched/rt: Remove default > > bandwidth control") caused a significant dip in his favourite > > benchmark of the day. Simply disabling dl_server cured things. > > > > His workload hammers the 0->1, 1->0 transitions, and the > > dl_server_{start,stop}() overhead kills it -- fairly obviously a bad > > idea in hind sight and all that. > > > > Change things around to only disable the dl_server when there has not > > been a fair task around for a whole period. Since the default period > > is 1 second, this ensures the benchmark never trips this, overhead > > gone. > > > > Fixes: 557a6bfc662c ("sched/fair: Add trivial fair server") > > Reported-by: Chris Mason > > Signed-off-by: Peter Zijlstra (Intel) > > Link: https://lkml.kernel.org/r/20250520101727.507378961@infradead.org > > Thanks for your patch, which is now commit cccb45d7c4295bbf > ("sched/deadline: Less agressive dl_server handling") upstream. > > This commit causes > > sched: DL replenish lagged too much > > to be printed after full user-space (Debian) start-up on m68k > (atari_defconfig running on ARAnyM). Reverting this commit and fixing > the small conflict gets rid of the message. Does https://lore.kernel.org/lkml/20250615131129.954975-1-kuyo.chang@mediatek.com/ help already (w/o the revert)? Best, Juri