From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-180.mta0.migadu.com [91.218.175.180]) (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 532C2425879 for ; Tue, 1 Sep 2026 03:11:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788232277; cv=none; b=JohAZg9ndgvw8H1JjiEGG6kDQONGVZoWDqfcvAgaHiXqTB9xtwuinhpvpSkxuTr5xMtbqPv58SFkFLb1XtrIGKv5MySUXuaKo2QeBwKUU8fvl1TgpMXd0BIGPoO/N8OL80E2f62GSsWV6mHBwK2XdIel2PEJe+uQ1OvVM+ue/M4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788232277; c=relaxed/simple; bh=s5oPWfvcaE1YMaxXsFJOTvk9No3nN8NYNIrkpi80+cM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ArsutGBwXsEGsPvGmd+yDs6HJE2PEr/wRzaa6OGnOgnZvROob5dYuNLmGk9QYW60E+5Orua6WRXj7YTfGdpMdGLtMEaltAmyOmgf5ClztKkb4Z2zPOEsl774D9DXj54/cxiA/VwoQTJb7xULXIXSUaKoHbcGL4MNLCR09u5eJxg= 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=GZs+7PTd; arc=none smtp.client-ip=91.218.175.180 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="GZs+7PTd" X-Envelope-To: bpf@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=s5oPWfvcaE1YMaxXsFJOTvk9No3nN8NYNIrkpi80+cM=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788232273; v=1; x=1788837073; b=GZs+7PTdJi7pNFnigosE7k6tUUzUolpPtnCzVO184D83S/B4IUwY/zFpw0OsIzslmNXC+Lf6 pKLj64RdBd+5imouiLK1eKZlPb9q4aSDetjNYXKZKwk15gVuWaFVGwLiEIzTwg/rHX93d4aKYfW RnQ4bEOXRrUpDpuiIWhpaMLM= X-Envelope-To: bpf@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id b250c1526b7c3aa9; Tue, 01 Sep 2026 03:11:13 +0000 X-Mizu-Trace-ID: b250c1526b7c3aa9 X-Migadu-Flow: FLOW_OUT From: Tao Cui To: tj@kernel.org Cc: void@manifault.com, arighi@nvidia.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] sched_ext: don't deliver duplicate ops.cgroup_set_idle() for same value Date: Tue, 1 Sep 2026 11:11:01 +0800 Message-ID: <20260901031101.731943-1-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 Signed-off-by: Tao Cui --- 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