From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-31.mta1.migadu.com [95.215.58.31]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 10AD21D9A5F for ; Tue, 1 Sep 2026 12:44:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.31 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788266666; cv=none; b=Y+BJa3MjrWGHP32wCzwQO49ZayzCqFVnLX47Lqsw9fFn80Uxjwb10TNaVbo1iLYeUyPY6oou1c9iUj/MlO4/LAVu9xv5Ogt27W5VVnVbUcjKAEXTIGH1IZGJ3OTJsd/VQ5tqpa6O3x/L+Htz1Z//qkU/mGdvAEwoHVLOEhjdocE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788266666; c=relaxed/simple; bh=4xYToF5MA/xkEqr/sq1dy954cS2PfO//LD1OfNLVaM0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=jwogOOnMJ79lITJZcNjH+w7pj42mvQ3DB71r7zWwIcvBhOWvIjoQzkHbjKdsamCYZxSiKyp9jcW6COYiDaIBmyReCuIjlLBvv/0mPmvBStYU2BzgZCRiwcKE9gXoX65THDZEFtGcMBKAwluFIKxEdpbujwShDdUmBWy4IfME7yA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=qVJsP0FQ; arc=none smtp.client-ip=95.215.58.31 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="qVJsP0FQ" X-Envelope-To: bpf@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=4xYToF5MA/xkEqr/sq1dy954cS2PfO//LD1OfNLVaM0=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788266662; v=1; x=1788871462; b=qVJsP0FQsZ3/CX8gVuA6NowMPsoz17VdmS5lsCIxH3q8zr8ue3QvuKfucP3EiTzlQIlmkgOR Mcwtcf2yE8oxpmbCkHOcrklAr5QiQMah1z+K6bD/GlN/YX15kMvvz5GaxJCahMktO0l1qyEZP8W f66s/XijNwkiZmG3RitXzOJE= X-Envelope-To: bpf@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 69d6713c70f1300e; Tue, 01 Sep 2026 12:44:21 +0000 X-Mizu-Trace-ID: 69d6713c70f1300e X-Migadu-Flow: FLOW_OUT From: Tao Cui To: tj@kernel.org, arighi@nvidia.com Cc: void@manifault.com, changwoo@igalia.com, michalblk@google.com, sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, cui.tao@linux.dev, Tao Cui Subject: [PATCH v2] sched_ext: don't deliver duplicate ops.cgroup_set_idle() for same value Date: Tue, 1 Sep 2026 20:43:47 +0800 Message-ID: <20260901124347.755904-1-cui.tao@linux.dev> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Tao Cui ops.cgroup_set_idle() is documented to be invoked when a cgroup transitions between idle and non-idle states, and scx_group_set_weight() already skips value-preserving writes. scx_group_set_idle() delivers every write unconditionally, so rewriting an already-correct cpu.idle value feeds the BPF scheduler a transition callback each time, which toggle- or accounting-based schedulers miscount. Mirror the weight guard and only deliver on an actual change. Verified with a probe scheduler printing each callback: rewriting cpu.idle=1 twice on an already-idle cgroup delivered two callbacks before and none after. Fixes: 347ed2d566da ("sched/ext: Implement cgroup_set_idle() callback") Link: https://lore.kernel.org/r/b53c61a1-4d7d-4232-941f-d48b0563d4ed@linux.dev Signed-off-by: Tao Cui Reviewed-by: Andrea Righi --- v1 -> v2: Fix the Link: msgid (missing @linux.dev, Andrea). kernel/sched/ext/ext.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 8041c87a3562..8b3625107b72 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -4933,7 +4933,8 @@ void scx_group_set_idle(struct task_group *tg, bool idle) percpu_down_read(&scx_cgroup_ops_rwsem); sch = scx_tg_knob_sched(tg); - if (scx_cgroup_enabled && sch && SCX_HAS_OP(sch, cgroup_set_idle)) + if (scx_cgroup_enabled && sch && SCX_HAS_OP(sch, cgroup_set_idle) && + tg->scx.sched_idle != idle) SCX_CALL_OP(sch, cgroup_set_idle, NULL, tg_cgrp(tg), idle); /* Update the task group's idle state */ -- 2.43.0