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Thu, 09 Jan 2025 16:22:53 -0800 (PST) Received: from [2620:0:1008:15:3031:2897:d7d8:ee1b] ([2620:0:1008:15:3031:2897:d7d8:ee1b]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-a31d5047fc8sm1845530a12.57.2025.01.09.16.22.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jan 2025 16:22:53 -0800 (PST) Date: Thu, 9 Jan 2025 16:22:52 -0800 (PST) From: David Rientjes To: Josh Don cc: Madadi Vineeth Reddy , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org Subject: Re: [patch 2/2] sched/debug: Remove need_resched ratelimiting for warnings In-Reply-To: Message-ID: <185e7b11-36aa-ffa8-7556-70a2840bd3b6@google.com> References: <77e42990-0ea3-fc53-8051-6856a92ad4d0@google.com> <4952e9fd-0d85-4d4d-9bf4-ae127d612008@linux.ibm.com> <85f483ed-845c-a25f-3558-e1a8629e9200@google.com> 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 On Thu, 9 Jan 2025, Josh Don wrote: > > Otherwise, please take a look, is this what you had in mind? > > I'm realizing now that we'll end up getting multiple splats for a > single very long stall (one per the warning threshold). We could fix > that by using a magic number rather than 0 here (such as U64_MAX), and > then teach resched_latency() to bail out on this value. > Ack, ok. I'll drop this patch because I see that there are existing users (at least one NVMe library) that cares about tuning both of these values with what appears to be some amount of thought: /sys/kernel/debug/sched/latency_warn_once=0 /sys/kernel/debug/sched/latency_warn_ms=16 and the intent was not that they get excessive output that they don't need or aren't expecting. Thanks for looking at this!