From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=90.155.50.34 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794501090; b=5T0EFIauUWHtvEokiz0NkYmtXamwXCB+EATmaRk/Lero7lSXF/e2ryCxykPqeSqHkUoE aU8q42n0mcf8rAYaondkJqx5GvLt0fV0Bp/+fZrQ4aasX1JTJmjWkW28y11WDupZGn5mT bYKzpyF7CYFhwIAJhKDroImA8ash53XSR0fe9wAbSlnNJBFR81eIwJlZxdcHy4PFcwtVc ojyYLuXsC/jZ8oquLLVfzPfYKfYeyfVYxP9RF9CjcjW/T87YylCNhqt95t3nq64PlUrvy AtckfUtiahCFCOQI/3d/CMRBYZmrvnyAA/LPm7kF6gDYjbQqi/lCjr8cOxT7P8mvoSA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794501090; h=DMARC-Filter:DKIM-Signature:Received:Received:Date:From:To:Cc: Subject:Message-ID:References:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; bh=NXHP9rMA5Jf8CLZLVoZt/ydGAK7mnAO+64jaDQMpezQ=; b=YJ3JfrCRhP6n5ZT+yG6RHE+GfXOidixvDkclnGVpAAFsD+qqosT6fUbGjalFcUuoqQAo 91gDhEXlEJgz8ePEcCFDLD6VzXAjIdvYc/zAK48j5CkYC6pAvZqlYsMkgpCSc6c3UcHxK +UjAGDLf6JzfBCNVEoodNXerlQC4CmBSixK6YvaKMHomfSh7zqaszhC2GWc34aDY63HDp 2MWaDxkK+ZOMPhEGUvMVpRJ7W+9EKZTq+QgPuEx4MfgciqV4lyDyjWw5qcnGd4a6fAFN9 XUzuXvm+XeXZKjDGW+00Xj7ZfOaBs2fHoFuqk7owsokL37MLBz3TTnDcIPPEDA9nAWg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=casper.20170209 header.b=Dg8xYo+i; arc=none smtp.remote-ip=90.155.50.34 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BDD3F606A89A; Thu, 12 Nov 2026 16:31:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org BDD3F606A89A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=casper.20170209 header.b=Dg8xYo+i DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=NXHP9rMA5Jf8CLZLVoZt/ydGAK7mnAO+64jaDQMpezQ=; b=Dg8xYo+i5qYGvtChOj6GMyc4ct mBnTLoGePkq+8YXRuP0TMs/x53PffymBSVL8jWc+zW2Xbq8KBsvBtw3fne7+5O+rkpk3acMZc8DQ5 W4jUoRslL/Xyck+MO+rgLS8gy7YnxhyQqlvvmy/UTP0fwofrbsc0pq9Hbtx1e+aY2mpwbyUHDyJyV t59j2XAdQ1C5d/JuC5v4t9VF11hOVZm5kb4b+mdak4OlPgWTRTceSr6GQvWj5d72IVHxeucKkPcyS e6wXM2ZzhAjbtPo8qTz/9zw4xfuFl02Qz21Xl0+yk682CX5uTFG5qarNKAuH4gy1WTyQy1fYcggcX TU/oK4SQ==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.100.1 #2 (Red Hat Linux)) id 1xRXhs-00000008xQd-19qT; Thu, 12 Nov 2026 16:31:24 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id B58ED303011; Thu, 12 Nov 2026 17:31:23 +0100 (CET) Date: Thu, 12 Nov 2026 17:31:23 +0100 From: Peter Zijlstra To: Andrea Righi Cc: Tao Cui , tj@kernel.org, void@manifault.com, changwoo@igalia.com, mingo@redhat.com, sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Tao Cui Subject: Re: [PATCH 2/2] sched_ext: Block a retained donor before PI deboost routes it back to sched_ext Message-ID: <20261112163123.GW1779021@noisy.programming.kicks-ass.net> References: <20261112144935.583937-1-cui.tao@linux.dev> <20261112144935.583937-3-cui.tao@linux.dev> <20261112152118.GD1813469@noisy.programming.kicks-ass.net> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Nov 12, 2026 at 05:05:04PM +0100, Andrea Righi wrote: > To recap, we ran into this while developing the proxy-exec support for > scx. Earlier versions were handling the PI deboost case too and we also > explored passing next_class into sched_change_begin(). But that didn't > make it into the final version and it was left as a future improvement, > to keep things simpler. > Would it make sense to revisit the old idea passing next_class into > sched_change_begin(), so we can handle entry into EXT consistently > before recording the queued/running state and replace the separate > class-entry preparation hooks? As per my follow up email, I think all we need is for the existing switching_to callback to return a boolean to indicate if the class is willing to accept blocked tasks.