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[36.225.99.238]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c8242cc1768sm1804956a12.32.2026.05.06.03.18.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 May 2026 03:18:15 -0700 (PDT) Date: Wed, 6 May 2026 18:18:11 +0800 From: Cheng-Yang Chou To: Tejun Heo Cc: "Paul E. McKenney" , sched-ext@lists.linux.dev, David Vernet , Andrea Righi , Changwoo Min , rcu@vger.kernel.org, Ching-Chun Huang , Chia-Ping Tsai Subject: Re: [PATCH v2 2/2] sched_ext: Fix exit_cpu accuracy for lockup paths Message-ID: <20260506181409.Gc6e5@cchengyang.duckdns.org> References: <20260504161543.674488-1-yphbchou0911@gmail.com> <20260504161543.674488-3-yphbchou0911@gmail.com> <20260505154006.G743b@cchengyang.duckdns.org> Precedence: bulk X-Mailing-List: rcu@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: Hi Tejun, On Mon, May 04, 2026 at 10:34:09PM -1000, Tejun Heo wrote: > On Tue, May 05, 2026 at 04:20:25PM +0800, Cheng-Yang Chou wrote: > ... > > > There might be more than one stalled CPU. You could pass in a cpumask_t > > > or similar to print all of them, or take the first or the last or > > > some such. > > > > sched_ext's exit_info carries a single s32 exit_cpu, so we can only > > record one CPU. Would taking the first stalled CPU be acceptable as a > > best-effort hint, or would you prefer we pass -1 and skip the CPU field > > entirely for the RCU stall paths? > > We carry only one cpu in exit_info but we can easily dump the cpumask and > prioritize dumping all the cpus in the mask. To confirm: are you suggesting scx_rcu_cpu_stall() take a cpumask, use cpumask_first() for exit_cpu, and dump the full mask in the exit message? Thanks. -- Cheers, Cheng-Yang