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 DB769281509; Tue, 21 Oct 2025 21:03:55 +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=1761080636; cv=none; b=GnsEStrF/+ZfTmjLGpuf3Z6SgJrdy/nRmGItBkd4obHWxDIlwB0YiZRdGl9139+4b5wbQEUlPYxFnC29leIr3LEBhLKjZD53jm4Ru6YxFSTY78Pd4KzTgS9eOTucauABfx1G6BVOLlGj99AzKY4xPNG1CL7NbX8EpF0+02JWUwo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761080636; c=relaxed/simple; bh=O/A7sYgHxed/PR88y0jCJjO8EnadjGl4dzz0Uf2M5O4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Kb8fcanwy5A3TCWHCCofzCnN/oG/OqlPV8ubUEfFC4svvvOycLdCZ3ahqiuSf/XL3Dz+47+vyX/hWa2JRVgatHspLlHcVDZTWxQIodwGI6mRaPwLKnFa25HgBbRC208rCus+s4ko/clT1x0nclOzPlO3dZcQSCwJoPMrSPbOtMo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ocfK0hXj; 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="ocfK0hXj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 526C6C4CEF1; Tue, 21 Oct 2025 21:03:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761080635; bh=O/A7sYgHxed/PR88y0jCJjO8EnadjGl4dzz0Uf2M5O4=; h=From:To:Cc:Subject:Date:From; b=ocfK0hXj6fnRtTi4m0BzgELTuLmEDPQD2mkRBtswTG/EcEnnw1vPqk6EojHMj6mHp aujQMR58ayKAqH/BgcurQwFK3x2AGW+qaowWEPa/k2uSEm3QGDjqWlFoJWjZhiExpx 62gFEoZn7qRAOepqLby8txg+uslHXoAox0Hk++1NUI3H5I/TiW4ap9P7lRtrzomrWq qU71UeMqkh05V82R0XuoKD/5gDTfIHdUgAwOhoUdVt5Vh/HptYPkiTOt9hjaWj/sW4 IwjmGG2A8e97HSppGmVT68CoVhKQrDDEMqzbWACDyITKAFWsfV03HwXlEBkD2H5Uu5 FDKCq3BYkQNTg== From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, sched-ext@lists.linux.dev, bpf@vger.kernel.org Subject: [PATCHSET sched_ext/for-6.19] sched_ext: Fix SCX_KICK_WAIT reliability Date: Tue, 21 Oct 2025 11:03:52 -1000 Message-ID: <20251021210354.89570-1-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 a target CPU to complete a reschedule, which is needed for implementing operations like core scheduling. This broke when scx_next_task_picked() was replaced with switch_class() in commit b999e365c298, because the sequence counter increment that SCX_KICK_WAIT depends on was no longer reliably called. This patchset fixes the regression by moving the sequence counter update to put_prev_task_scx() and refining the semantics to work correctly with the updated scheduler structure. The first patch adds a prerequisite check to skip kicking CPUs running higher sched classes, which SCX has no control over. Based on sched_ext/for-6.19 (2dbbdeda77a6). 0001 sched_ext: Don't kick CPUs running higher classes 0002 sched_ext: Fix SCX_KICK_WAIT to work reliably Git tree: git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-fix-kick_wait kernel/sched/ext.c | 42 ++++++++++++++++++++++++++---------------- kernel/sched/ext_internal.h | 6 ++++-- 2 files changed, 30 insertions(+), 18 deletions(-) -- tejun