From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E7B483E16A9 for ; Thu, 25 Jun 2026 12:44:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782391443; cv=none; b=EtefJJ61Jr5X9BP4EufteBsBShe9XT6ojZFf6PtB8eHloJ61Z807gHvHbEbU8X8DL9O4ZTP38SRbHjx+0VtO1qeSc3KVfW5ulhZ+/tgS0Al4BrDJ0IgJDJHosdX8MNlEsldtYVyWMuQWwJyTbQxc0fTDL8IXxopBAZMa+chPPaM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782391443; c=relaxed/simple; bh=/H0d7/gkcxXziaSZLWbntI35eZyKoUfTVDBX/2TT+bc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=YnNk3Q5OhMLgrVCyn0iOfN/4wxRsTrX7XqZj7WmwcZ8D5GnY+YPy3Quu75AwZ4HO7jo2mVLYgpA1ffIFY37cn/5TYFW3Gcd3BxwLB5kovjlHZgPDyGc9S3goO08k+70e+kE1TLOG5jfDiGH6VBqzyV66sV0PDQBHxzLh8y69WNA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=cyiZ2J6S; arc=none smtp.client-ip=90.155.92.199 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.b="cyiZ2J6S" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=kScZCI0gtPf+XJz97Q8kPEI8ikc/8GyxwAVPRokXK4c=; b=cyiZ2J6S8UsuGg15YyI3gr9Q4A vy11h47opX7EG5UBBHSSbHb5mDAfVNJjg5G1Kqj62tNy57qM3aqCUozYbvVSpdkklqwQkiQ7DAZxD NQPrkk8Ydw4QPbRUWSAdMwIMRDYw0XdEsuuuNw7o9kZtM/1MRumxZ737hPI8gMnBXmzfH4s6yBO57 ZZHJtqKaMDz7wr6u3Psp25kWR7IumgWlh+bW942u2nTloKBWwrNc/87JpLEEZ8mjMBXQE4FAzqPxS lGgjW6mYew6OyuXH6i+XxMYrW+CKZrm5C+KSo4oFg4O614Y614XUQX0Haq61Wz4CPHrCbt1jcnAbG RaM0vKhA==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.99.2 #2 (Red Hat Linux)) id 1wcjQu-00000003clN-0Tek; Thu, 25 Jun 2026 12:43:53 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 48DD23005AF; Thu, 25 Jun 2026 14:43:51 +0200 (CEST) Date: Thu, 25 Jun 2026 14:43:51 +0200 From: Peter Zijlstra To: Vincent Guittot Cc: K Prateek Nayak , mingo@redhat.com, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, linux-kernel@vger.kernel.org, qyousef@layalina.io Subject: Re: [PATCH 1/6 v3] sched/fair: Set next buddy for preempt short Message-ID: <20260625124351.GD1181229@noisy.programming.kicks-ass.net> References: <20260624151229.1710703-1-vincent.guittot@linaro.org> <20260624151229.1710703-2-vincent.guittot@linaro.org> <07c84814-bbca-4c94-aebb-5ac0858efcfc@amd.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 Content-Disposition: inline In-Reply-To: On Thu, Jun 25, 2026 at 02:40:34PM +0200, Vincent Guittot wrote: > On Thu, 25 Jun 2026 at 08:24, K Prateek Nayak wrote: > > > > Hello Vincent, > > > > On 6/24/2026 8:42 PM, Vincent Guittot wrote: > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > > index d78467ec6ee1..83bce5a04f3d 100644 > > > --- a/kernel/sched/fair.c > > > +++ b/kernel/sched/fair.c > > > @@ -9903,7 +9903,7 @@ static void wakeup_preempt_fair(struct rq *rq, struct task_struct *p, int wake_f > > > preempt: > > > if (preempt_action == PREEMPT_WAKEUP_SHORT) { > > > cancel_protect_slice(se); > > > - clear_buddies(cfs_rq, se); > > > + set_next_buddy(&p->se); > > > } > > > > On a tangential note, I just noticed set_preempt_buddy() has two unused > > parameters. Seems to have been like that since it was introduced in > > commit e837456fdca8 ("sched/fair: Reimplement NEXT_BUDDY to align with > > EEVDF goals"). > > > > Perhaps this can be included in the series too as a cleanup: > > I would even go further and remove it. The NEXT_BUDDY feature is broken anyway I thought Mel wanted to try again, but he's been somewhat silent on matters. Mel?