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 4842F81727 for ; Mon, 7 Oct 2024 20:20:25 +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=1728332426; cv=none; b=Ltxjkal+FIPL7grSf1aHg6ViRivTRSegB/erai4o7ThJV4JVz53fhHWdc1Lp9s6NmbmB7iFjA49IxifMTD/fYuCATaLpeYM7WKHFfchSh9nr84yWlL7CWyLXFvY4t/ifDOFL1bKUdK1LAMa4XNEnC8DaeJYHLMssyEDkTOv/qjE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728332426; c=relaxed/simple; bh=EgSfqyvN9ek1mlSGDVahGdP3YsJgNByFt+mLCzx71V0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iAucSrgaWp9iNCAHv6jiddDNeGSAVTcTcsaqRJK/HaSjOQjwKym5zyRF71cjSVK9cdhdW7g8r2RYeYuQAhRRYgPgodCgxtToD+DKm8FZsctP1fZ9eek7iOcZwHKl1o4S0Rmf9Rk6wO6QgjUxneDRywl2/mS09IUNDL9WtSJziF8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f6s72RTu; 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="f6s72RTu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF184C4CEC6; Mon, 7 Oct 2024 20:20:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728332425; bh=EgSfqyvN9ek1mlSGDVahGdP3YsJgNByFt+mLCzx71V0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=f6s72RTuMC+QkJePD6IBp+vWwmtlScA65hHx3XEHvGS9XnQlzNiHI8WkZ4/2pPz3+ FqLgeA2Ao/3jHLmN9tx2vzZ/rJWSPCQAMbFWzZ4TxeceRqJkty8MlfqkQKp32dgHW6 WhUp73xh5aa74avdGtqVeSMgSbEkvFzPVPkaqNDbXFfmbWJTqEiDcGgLW9AhzsHO5T 4jtMECqhcH2tdRG4qJjtyRG110lgho76TAd9bPq4DuJMsj5Ms0eVvAERkJ2g4trveJ Z4Qn3KhyRkRksa9c8vUyeStwK8kEDSIhYzYxETrWPROK3Fl7LLPSdo3qIbWbzP4WO6 OkZ+A6/8abG1A== Date: Mon, 7 Oct 2024 10:20:24 -1000 From: Tejun Heo To: void@manifault.com, peterz@infradead.org, mingo@redhat.com Cc: kernel-team@meta.com, linux-kernel@vger.kernel.org, sched-ext@meta.com Subject: Re: [PATCHSET sched/urgent, sched_ext/for-6.12-fixes] sched/core, sched_ext: Add ENQUEUE_RQ_SELECTED to fix ->select_task_rq() skip detection in sched_ext schedulers Message-ID: References: <20240927234838.152112-1-tj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240927234838.152112-1-tj@kernel.org> On Fri, Sep 27, 2024 at 01:46:10PM -1000, Tejun Heo wrote: > During ttwu, ->select_task_rq() can be skipped if only one CPU is allowed or > migration is disabled. sched_ext schedulers may perform operations such as > direct dispatch from ->select_task_rq() path and it is useful for them to > know whether ->select_task_rq() was skipped in the ->enqueue_task() path. > > Currently, sched_ext schedulers are using ENQUEUE_WAKEUP for this purpose > and end up assuming incorrectly that ->select_task_rq() was called for tasks > that are bound to a single CPU or migration disabled. > > This patchset adds ENQUEUE_RQ_SELECTED to indicate whether > ->select_task_rq() was called to ->enqueue_task() and propagate that to > sched_ext schedulers so that they can reliably detect whether > ->select_task_rq() was skipped. > > Peter, please let me know how 0001-0002 should be routed. If they get > applied to sched/urgent (when it opens), I'll pull it into > sched_ext/for-6.12-fixes and apply 0003 on top. If you'd prefer, I can take > all three through sched_ext/for-6.12-fixes too. > > This patchset contains the following patches: > > 0001-sched-core-Make-select_task_rq-take-the-pointer-to-w.patch > 0002-sched-core-Add-ENQUEUE_RQ_SELECTED-to-indicate-wheth.patch > 0003-sched_ext-scx_qmap-Add-and-use-SCX_ENQ_CPU_SELECTED.patch > > 0001-0002 are sched/core patches to add ENQUEUE_RQ_SELECTED. > > 0003 makes sched_ext propagate the flag as SCX_ENQ_CPU_SELECTED and fix > scx_qmap using the new flag. Applied 1-3 to sched_ext/for-6.12-fixes. Thanks. -- tejun