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 913F92FBDFB; Wed, 22 Oct 2025 20:50:02 +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=1761166203; cv=none; b=ujQE4U3P0oVB6sQpIia3dPMpyp94NR098U9du/TguQwC5oQRP4fAHjljgpQpxPkb3G8AILYR4ZRnN82M6Zjl/DGorOFN+egF4XHfcR8h+5uzP1fwTV6+PWFIx+aURzoW4mfrQ+TA4IhvF9Ygj4Gio45PB5LoYNugNSvPTdP1cGU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761166203; c=relaxed/simple; bh=+ocb1AeN8Q9xIBuddW6IcBX4wP7fBSwoIGna7HpsBWA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=poVsB47IRTegGfyWTczT/iPvNCM6PRAoJ/cyA8EDvRbh0J2bOMEWNTqlQTwWb5BH4vHrhMSa/NwpC4sPdoGOD12UmS+1qQZUeao3ZZP9ApHDRKLOJsue821vDa7sOuLe29iQqWQJ9xa2RClo7ZpHPpjJpyZztlmbVjJOkGJgxb4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WRJBDbsh; 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="WRJBDbsh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC58AC4CEE7; Wed, 22 Oct 2025 20:50:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761166202; bh=+ocb1AeN8Q9xIBuddW6IcBX4wP7fBSwoIGna7HpsBWA=; h=From:To:Cc:Subject:Date:From; b=WRJBDbshmffFjw4BFqMgVL7JyjwsglQzmJlnXHCVpsBha72VwFgWyse5FJ3Co+o8O rEA7OLPSRLRQazamO+I7Qw2mSu8L7VwwCmh/56e57pYJoyXE67nGyxqi/f79hE56Y5 dFmdt3gPaDtwIzv59BMtAVVaHTexnQb38QM+RTu4i+7hLi1huAcW1mtbFeqs4gu8R2 90JsxPSFl7Xj43jIgKfeDz1eDLjTCobQhAlWHX1BwT+a8W/UxnhUyiVR9kG8U+uSc8 4+OEHwFrRGbbeKeXIurhcwJ8RlFFUku70Aw9LTwHOuP9DmupawW7JPwT4Kpdeb0o+W MZ/iJYaqbeWVw== From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min Cc: linux-kernel@vger.kernel.org, sched-ext@lists.linux.dev, Peter Zijlstra Subject: [PATCHSET v2 sched_ext/for-6.19] sched_ext: Fix SCX_KICK_WAIT reliability Date: Wed, 22 Oct 2025 10:49:57 -1000 Message-ID: <20251022205000.843899-1-tj@kernel.org> X-Mailer: git-send-email 2.51.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit SCX_KICK_WAIT is used to synchronously wait for the target CPU to complete a reschedule and can be used to implement operations like core scheduling. However, recent scheduler refactorings broke its reliability. This series fixes the issue and improves the code clarity. v2: - In patch #2, also increment pnt_seq in pick_task_scx() to handle same-task re-selection (Andrea Righi). - In patch #2, use smp_cond_load_acquire() for the busy-wait loop for better architecture optimization (Peter Zijlstra). - Added patch #3 to rename pnt_seq to kick_sync for clarity. v1: http://lkml.kernel.org/r/20251021210354.89570-1-tj@kernel.org Based on sched_ext/for-6.19 (2dbbdeda77a6). 1 sched_ext: Don't kick CPUs running higher classes 2 sched_ext: Fix SCX_KICK_WAIT to work reliably 3 sched_ext: Rename pnt_seq to kick_sync Git tree: git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-fix-kick_wait kernel/sched/ext.c | 129 ++++++++++++++++++++++++-------------------- kernel/sched/ext_internal.h | 6 ++- kernel/sched/sched.h | 2 +- 3 files changed, 75 insertions(+), 62 deletions(-) -- tejun