From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=90.155.92.199 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794496220; b=vNGq6m7jF84pDjTCoF67QBJr30ypB+BuupdCZ0PxWXqtto6CeFDtlmc3Gz6EW7ZjqnZ+ ff4Q+g2teCpv3n495xdSDTPYKEJcyE7VIPoP+gPTY2EssLOXGnc2sJFiSz/ut5Ri8DeJj 1aawvDm9XjPhvs6ZAVTYzFdKTWo0hsFPEt68Wo3AmsCdsbKOHC7zFEE3Pomkf+0h/OPoe EApixMqkaq8TKRSxA7taIGTVmKB1jeqQhOdQHyHhQmIet+fvXJChIXwggmMsMaWUXfWvs eZ3TW4MfZQXKlppgiQvnbV3CEwircYRcwwx7qKMumCg7yK5Rum5lamUUifc942pYg5Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794496220; 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=reuptjqlwF1l2qQU+pOSgmAUmz0f784Lhxxdtt7p17o=; b=f6LNtDOBPl9sZLVHkVBAblFOmoU63ohYkZSV9oUTLHVOcA0Fr6s9lJRw3VrawhJW6KLT NrRBdLsXIIQDePhvZ4VhyyA2i4pvyIhYAuXz2srCMgH2M/CZ2GUzoTAdbJa0/eL76nd0X MriMusyDlfXLZuOlo0tK+BC48z1jiAYjAqmrK6EThoVojSCPc1a9gRbkwkyESL2T86quW Bj+6r0P3jXy0Ym2hpNyZi6/fgJhdq4r8u2gKI5vedJDJP/wHm8Y+6gn4hjNaFoyDQB0y3 yLJoYlATcSCFM008uezRYojighP2M57leGhM7mb0P2Kef7G2cVivE4OMHYT8uplbCOg== 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=desiato.20200630 header.b=U8ZCOrxR; arc=none smtp.remote-ip=90.155.92.199 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 672FB606A31C for ; Thu, 12 Nov 2026 15:10:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 672FB606A31C 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=desiato.20200630 header.b=U8ZCOrxR 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=reuptjqlwF1l2qQU+pOSgmAUmz0f784Lhxxdtt7p17o=; b=U8ZCOrxR2ArtBnFgGjrTECJ99W 16d/aQh0WPOBPpOUkbCQLdHxt20l56FW+wG5/Gq4V/Ytg3vzAgKXkulctJGR2zcOEJLzoW8nW8q96 qoXBuJHQL0QxfDW/eAMM5Prq+4mlX239JUztUGT9Q7d+kGaH2LgDqmaJY8mkMUG1yKLfZBQ0z873S fYyBFRvUZ4DGytXU1LCx8RWWyr4M7QHQ2I2+tX38WlBluN7+n3GYEi2CzjeOTV/q0n7wsEzjZniRr sC33Bf9/9zm2mxA536TxpB5etA/JEdnY0JbiTyquC7Mv7pMFltwK0hkOXHgn3Z3hjpNaebvDGfKk0 hhwiZF/w==; 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 4.100.1 #2 (Red Hat Linux)) id 1xRWRH-0000000ATro-4BsO; Thu, 12 Nov 2026 15:10:11 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 9C6DF30057E; Thu, 12 Nov 2026 16:10:10 +0100 (CET) Date: Thu, 12 Nov 2026 16:10:10 +0100 From: Peter Zijlstra To: Kayra Cizmeci Cc: mingo@kernel.org, linux-kernel@vger.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, joshdon@google.com, tj@kernel.org, jakub@okonski.org Subject: Re: [PATCH 2/3] sched/fair: Make cfs_rq::idle the sum of ancestor tg::idle Message-ID: <20261112151010.GB1813469@noisy.programming.kicks-ass.net> References: <20261105165525.011876858@infradead.org> <20261105170157.616859418@infradead.org> 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 Thu, Nov 12, 2026 at 05:02:27PM +0300, Kayra Cizmeci wrote: > :-(. > > Look here: https://lore.kernel.org/oe-kbuild-all/202611121431.06YgiErz-lkp@intel.com/ > > On Thu, Nov 05, 2026 at 05:55:27PM +0100, Peter Zijlstra wrote: > > Rather than keeping cfs_rq::idle as a copy of tg::idle, make it the sum of > > all ancestor tg::idle. This makes it trivial to tell if the current cgroup > > is marked idle somewhere along its ancestral path. > > > > This makes se_id_idle() behave differently. Notably is will now be true > > when there is a idle cgroup anywhere in the ancestor path. This > > addresses an issue where preemption of cgroup::idle was overlooked when > > flattening the runqueue. > > > > Fixes: 85570f10a4c6 ("sched/eevdf: Move to a single runqueue") > > Signed-off-by: Peter Zijlstra (Intel) > > --- > > kernel/sched/core.c | 2 - > > kernel/sched/debug.c | 1 > > kernel/sched/fair.c | 73 ++++++++++++++++++++++++++++++++------------------- > > kernel/sched/sched.h | 4 +- > > 4 files changed, 50 insertions(+), 30 deletions(-) > > > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -8970,7 +8970,7 @@ void __init sched_init(void) > > rq->nr_running = 0; > > rq->calc_load_active = 0; > > rq->calc_load_update = jiffies + LOAD_FREQ; > > - init_cfs_rq(&rq->cfs); > > + init_cfs_rq(&rq->cfs, NULL); > > init_rt_rq(&rq->rt); > > init_dl_rq(&rq->dl); > > #ifdef CONFIG_FAIR_GROUP_SCHED > > --- a/kernel/sched/debug.c > > +++ b/kernel/sched/debug.c > > @@ -1090,6 +1090,7 @@ void print_cfs_rq(struct seq_file *m, in > > SEQ_printf(m, " .%-30s: %d\n", "h_nr_runnable", cfs_rq->h_nr_runnable); > > SEQ_printf(m, " .%-30s: %d\n", "h_nr_queued", cfs_rq->h_nr_queued); > > SEQ_printf(m, " .%-30s: %d\n", "h_nr_idle", cfs_rq->h_nr_idle); > > + SEQ_printf(m, " .%-30s: %d\n", "idle", cfs_rq->idle); > > idle is only in the CONFIG_FAIR_GROUP_SCHED :-(. > So as the robot says, this breaks compiling in !CONFIG_FAIR_GROUP_SCHED. > > AFAICT tho, moving this down below in CONFIG_FAIR_GROUP_SCHED next to > h_load and other guys will solve the issue no? Yeah, pushed out again, lets see if the robots find more ;-)