From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=90.155.50.34 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794412054; b=wYlW7z+E5t+tAUMNp0KwCIFomaNKb71vMlVWc5eatfPDzMhWGLovJjEb6xNg9gQ7UJ1S pwjtz462dnYFeEGqmVpRJzew84R6niIdi1wybQIPcsSdTsiZG+jzHkAdPzUnepNS0nbFL AGyM8gLXRDLPpwnsg55tDftJeE8ERZv4XSyK5sMgXRkst1innjBMNiQCwgimHvn+i41D0 Qe0RosKPlfejKnnebZLuSBzfjRAejWt87qZL50EIgpYRXr7X/qkSdwT0oZrhMidiXZZRT qqpP8VW+emZdohlvS3RPrz0LOurAJNFNTbK3BUJMTGRo+4Xz6cSeE5Ici0XTwsM9oSw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794412054; h=DMARC-Filter:DKIM-Signature:Received:Received:Date:From:To:Cc: Subject:Message-ID:References:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; bh=8JFpaAsG9vSxGmUvW8VP+sDnwaF6mPE4UBPNJaxYmJs=; b=OPdzlLPfDF6VeJs8RJievpWliJa78XC/ESgiSnpqogjICwTpdP68uWrbJidhz8XY6qmi rvpidQvVuA+5xrL/xBpJiTaeoyXO0HdoOF5MZMKZ/Dc20u6Xeu6bJ0Bp3EYOwk+MfEfm4 1mByiAPHqqwaXsNcZC34bQTm08/5yaPX47SdFVU3swWZWq5Qxl3syqXfJO8wXKev1meAw G2ruDJQxA/26Exwo3J6UgMf0ByWuXDcfsqNYE/HI8C4vJ+AZ+vluY58/idLa/hE2usRZ+ eSfZKWiVAmUWVlm5umd3lW7P8Hbzf5Wip+9YsmP+Wx7P1vFRw748/98LQt9XaoiAJdA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=casper.20170209 header.b=DWSzvPaB; arc=none smtp.remote-ip=90.155.50.34 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5A4B9606A321 for ; Wed, 11 Nov 2026 15:47:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 5A4B9606A321 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=casper.20170209 header.b=DWSzvPaB DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=8JFpaAsG9vSxGmUvW8VP+sDnwaF6mPE4UBPNJaxYmJs=; b=DWSzvPaBR+QkdbcO0fAC9kUOxL bIFreNzt8kOXDyuaL/vWNlhuQTY/1vpUKTA2t854106izH+ldcJ2BQTmreGPmRRqguUZ0+14fWW6y FfY0KUFSOstqkvTjefj3PGLaU4h+zhhmnttFkAVHakt12DyeDJk5+5UZIpQWfs28QrIhDwrvqFXEt Zoz2yses9jxUbcMJvOJesRSJDfA1ISwnTB/FqvYqoA1yqn3lIZOSw4rB6axniGrVzOhy95qqwDvr2 eg7CZ7P2A6TFLKExtYEfLUcZSbvXY2VV/09qX1EAfFI+5cAAzqxcMX234m24E+94zy1i6nHbnmFS4 7H6xsGow==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.100.1 #2 (Red Hat Linux)) id 1xRAXl-0000000B9Z9-0HHV; Wed, 11 Nov 2026 15:47:25 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 410D230031E; Wed, 11 Nov 2026 16:47:24 +0100 (CET) Date: Wed, 11 Nov 2026 16:47:24 +0100 From: Peter Zijlstra To: Kayra Cizmeci Cc: Tejun Heo , mingo@kernel.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, linux-kernel@vger.kernel.org, ziqianlu@bytedance.com Subject: Re: [PATCH v2 12/12] sched: Remove sched_class::balance() Message-ID: <20261111154724.GO1779021@noisy.programming.kicks-ass.net> References: <20261107115913.261163891@infradead.org> <20261107120208.153536827@infradead.org> <20261111130512.GO2668200@noisy.programming.kicks-ass.net> <20261111131152.GD2669272@noisy.programming.kicks-ass.net> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Nov 11, 2026 at 05:57:01PM +0300, Kayra Cizmeci wrote: > Hi Peter! > Let's say a fair task named TA is working in CPU1, a DL task named DA is > waking up. We enter the normal wakeup path, and call enqueue_task_dl() > and from there enqueue_dl_entity(). enqueue_dl_entity() sets next_class > to dl_sched_class. Later enqueue, when we call wakeup_preempt TA does > not gets preempted because: > > void wakeup_preempt(struct rq *rq, struct task_struct *p, int flags) > { > struct task_struct *donor = rq->donor; > > if (p->sched_class == rq->next_class) { > rq->next_class->wakeup_preempt(rq, p, flags); > Gah, you're right. This don't work right. Let me try again.