From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4E78E2D3A75 for ; Fri, 24 Oct 2025 13:25:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761312353; cv=none; b=oIvU8XNjsODIGgXOZqrD2S5KIE2cv4EJHcWnV2FSXlq76Y3/joMGdwgKoHqL7zvvICQfywWiijnibLBUiy+z3xgEtBR25p/i2n6NhJ3qk0WcdGX/V1ZfZw2259tjePNbNzdEtRTZQ1MQgvBw9cxLo2+rDKt2f2FGpiFIYt0kIGo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761312353; c=relaxed/simple; bh=ca4FOp589+Z4avUlf5XZZrsqGiyG4LYV8lB6Ys4hvEE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=VjVUXl3EYKlwhkcBxfvRhUT9AhUi4h/91+vSyKQFy2MwIZM6YikjCvgFFVIRGGV5OcC4BNaYGegJ5dofEczX8QzTMgyZ2HkfW+B62AWVYFz+9CypNdRei5zzfT6jhdhqtpZYJPxfpbLDG+nhhpEwkNS5wwf8DzLk+VrkBll2DGY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pAaP7ZVp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="pAaP7ZVp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B6DB9C4CEF1; Fri, 24 Oct 2025 13:25:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761312352; bh=ca4FOp589+Z4avUlf5XZZrsqGiyG4LYV8lB6Ys4hvEE=; h=From:To:Cc:Subject:Date:From; b=pAaP7ZVpb0nfipPcxcDbibGEG7uph2IJY7OOndAYondpqpf1aSEhq9xJQDnhvIMXr LKWqZ1tbKaM0hFFm5QzeO+aXWqWm0JvAZO2afyClyPFXfSkSR5084yeuwAyDP0gHgJ FgshhS6ZJBygZco4mpGk1NI8hC4YRjc6+bQ33iKYZS74qWKVzDxmu5DBQPG/U9hZnI iQwC1d6PWjqT+klivjYt40GTInhCShJpGU40+0mMt9YmmiovMGs89a7m2aZXNvRUAB Gt3CriFlc2aHi01CI15vdKrHVl1Xbbbzuz9bbULTqAu6I9jUDbgKVHCvwa9OUcbq0p A7ueMRlQJsQYA== From: Frederic Weisbecker To: Thomas Gleixner Cc: LKML , Frederic Weisbecker , Anna-Maria Behnsen Subject: [PATCH 0/6] timers/migration: Fix NUMA trees + cleanups Date: Fri, 24 Oct 2025 15:25:30 +0200 Message-ID: <20251024132536.39841-1-frederic@kernel.org> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi, A while ago I found out that NUMA tree layout had flaws but I thought it was only about rare setups. Having had a closer look while thinking about the big.LITTLE handling, I realized the NUMA timer tree are actually imbalanced in many cases, except perhaps when 0-7 CPUs are lucky enough to belong to the same node, and yet up to a certain amount of CPUs. Here is a fix proposal, plus a bunch of cleanups. git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git timers/core HEAD: 4adecc004d35dbe8a48df3d23ed2b8cf42772716 Thanks, Frederic --- Frederic Weisbecker (6): timers/migration: Convert "while" loops to use "for" timers/migration: Remove locking on group connection timers/migration: Fix imbalanced NUMA trees timers/migration: Assert that hotplug preparing CPU is part of stable active hierarchy timers/migration: Remove unused "cpu" parameter from tmigr_get_group() timers/migration: Remove dead code handling idle CPU checking for remote timers kernel/time/timer_migration.c | 279 ++++++++++++++++++++++-------------------- 1 file changed, 143 insertions(+), 136 deletions(-)