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[141.239.149.160]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1ff59059fa5sm18810485ad.125.2024.08.02.09.09.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 Aug 2024 09:09:05 -0700 (PDT) Sender: Tejun Heo Date: Fri, 2 Aug 2024 06:09:03 -1000 From: Tejun Heo To: Peter Zijlstra Cc: Linus Torvalds , linux-kernel@vger.kernel.org, David Vernet , Ingo Molnar , Alexei Starovoitov , Thomas Gleixner Subject: Re: [GIT PULL] sched_ext: Initial pull request for v6.11 Message-ID: References: <20240723163358.GM26750@noisy.programming.kicks-ass.net> <20240724085221.GO26750@noisy.programming.kicks-ass.net> <20240802111018.GI39708@noisy.programming.kicks-ass.net> 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: <20240802111018.GI39708@noisy.programming.kicks-ass.net> Hello, On Fri, Aug 02, 2024 at 01:10:18PM +0200, Peter Zijlstra wrote: > On Tue, Jul 30, 2024 at 03:36:27PM -1000, Tejun Heo wrote: ... > > Maybe, but at the same time, it's also just some isolated cruft that enables > > UP support, so both sides of the scale seem similarly light-weight? I lean > > towards "why not support it?" but don't feel particularly strongly about it. > > So you're basically looking for something like this? > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index a9f655025607..69ec02a28117 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -5772,7 +5772,6 @@ static inline void schedule_debug(struct task_struct *prev, bool preempt) > static void put_prev_task_balance(struct rq *rq, struct task_struct *prev, > struct rq_flags *rf) > { > -#ifdef CONFIG_SMP > const struct sched_class *class; > /* > * We must do the balancing pass before put_prev_task(), such > @@ -5783,10 +5782,9 @@ static void put_prev_task_balance(struct rq *rq, struct task_struct *prev, > * a runnable task of @class priority or higher. > */ > for_class_range(class, prev->sched_class, &idle_sched_class) { > - if (class->balance(rq, prev, rf)) > + if (class->balance && class->balance(rq, prev, rf)) > break; > } > -#endif > > put_prev_task(rq, prev); > } > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index 4c36cc680361..40f3dc436f4f 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -2296,8 +2296,8 @@ struct sched_class { > void (*put_prev_task)(struct rq *rq, struct task_struct *p); > void (*set_next_task)(struct rq *rq, struct task_struct *p, bool first); > > -#ifdef CONFIG_SMP > int (*balance)(struct rq *rq, struct task_struct *prev, struct rq_flags *rf); > +#ifdef CONFIG_SMP > int (*select_task_rq)(struct task_struct *p, int task_cpu, int flags); > > struct task_struct * (*pick_task)(struct rq *rq); Yes, exactly. This is how it was implemented in the first RFC patchset. If you're okay with the above, I'd love to go back to it. Thanks. -- tejun