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 BBE8A285CB3 for ; Thu, 23 Apr 2026 16:54:01 +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=1776963241; cv=none; b=KKR60P5t8n5stguXdm85+5YT/TjN/wAE4vRTTtEkC9nU5KHd31CPhodsppSdrNvg5TzarrgtULvrmKDiw4CHfxn8YtVTePjG+1iH03ozJ8hSY53ugA2UkjI7mLlSgDvjquqRYP3TY2xX2OCmPvZ62aSiXAcq6U2bgJq3IIWr34k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776963241; c=relaxed/simple; bh=m9CDJDYjB+Oyl05ifZPgF9iNvGZePz2TbJcMdtVw5Og=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=SIhe7upKaOaU0/tBWzQMPBCsr3VXIrO4pNmx374Uy9kIgqIMWpCMf7z/fbpBbz4gcQdOMZWtMa3qxjwJudl2M7h10JMTdoTyCSw0FVMMQvD52JeQdC+IbKwUPrheFuFLV/Oqz0I+jxoJgG+x2F11k+goPnVTNXqsz/IWgt9ZLUU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f0J2adh3; 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="f0J2adh3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 209D9C2BCAF; Thu, 23 Apr 2026 16:53:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776963241; bh=m9CDJDYjB+Oyl05ifZPgF9iNvGZePz2TbJcMdtVw5Og=; h=From:To:Cc:Subject:Date:From; b=f0J2adh3hJqCKUnkQt82n3pQr71Y76N20q4vG/oL2UJrPKn+TpxRnvXLjLH7f7bev yirrSNNf9HNUle21C8+mVVIDL5E4X0//ec2PdjhrdLIEicE9FANvKeHtWGu3Kxw2y+ VeJaB5wgIxtETN93xMnsCyHJ2zv+gUB5jk6rzyjzKRL5LfyDKFcDsqXFZ+PyKPZhro oJYUzia1xIp6fO7Tp6yubbE4Neu8YCAbWJeWiaj/jjkjTdLwPcxURh6zhDE/2rYjTZ VaQl/yfNv/pc8w4s1e6Q9rpZPlYfR8u2bU7CY9H3rLGZOqjzd5KDMH4h21R/gs/XOl XsVJNaYJ3Doow== From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Thomas Gleixner , Anna-Maria Behnsen , Sehee Jeong Subject: [PATCH 0/6] timers/migration: Handle heterogenous CPU capacities Date: Thu, 23 Apr 2026 18:53:48 +0200 Message-ID: <20260423165354.95152-1-frederic@kernel.org> X-Mailer: git-send-email 2.53.0 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, This is a late follow-up after: https://lore.kernel.org/lkml/20250910074251.8148-1-sehee1.jeong@samsung.com/ To summarize, heterogenous capacity CPUs migrate their timers indifferently between big and little CPUs. And this happens to be often migrated to big CPUs, increasing their idle target residency. Thomas proposed to isolate the hierarchy between big and little CPUs. So here is a try. Note I haven't tested on real heterogenous hardware so if you have it, please test it! git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git timers/core HEAD: f0a87af6dab6f3a6dd8a603a2b9d7dcc86fd50e4 Thanks, Frederic --- Frederic Weisbecker (6): timers/migration: Fix another hotplug activation race timers/migration: Abstract out hierarchy to prepare for CPU capacity awareness timers/migration: Track CPUs in a hierarchy timers/migration: Split per-capacity hierarchies timers/migration: Handle capacity in connect tracepoints scripts/timers: Add timer_migration_tree.py include/trace/events/timer_migration.h | 24 ++-- kernel/time/timer_migration.c | 246 ++++++++++++++++++++++++--------- kernel/time/timer_migration.h | 19 +++ scripts/timer_migration_tree.py | 122 ++++++++++++++++ 4 files changed, 337 insertions(+), 74 deletions(-)