From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 4EB073F1ABD; Tue, 14 Jul 2026 08:08:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784016492; cv=none; b=XAtz8UsS56meyFHLOH+sKPq/EMcyIMaSFESf7X7CNTjFRlla5Oucb0ZK/Nfr/W18uDDnRlghWRtw+f1dGsg7H9ealHm1UaNgiV2hy/7EiHMEmzDMnD4yFy8Oz4SVsBPBMCi62gqPlPmzvokvlp+RAK3LzrWTkFmtiCwfgghadTs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784016492; c=relaxed/simple; bh=mHDh0GnyQIdNot8LznGvaUdV6obqTWq8j3Cw3Y+mxv8=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References; b=AAH8rQcCty7MNr2YFY8wAuF72yp2NxRVXOvGpySMvRJkykwLRneF98qW3ktWdXm2uQw07hJAQLACyaPW1+sHBs57I4PU6KeiJ1W+zXVIlTzNUdbAkKtu9ocBADz3VrXAxiJHRtMMXjOizHwCfwHR6Zn8CYVmcIqQVZH48lCjvw8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MQtx6gBd; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MQtx6gBd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3C811F000E9; Tue, 14 Jul 2026 08:08:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784016491; bh=L7w7aaKI3KehmvKi5swepEnNdbiXBBEuNWbpoVpH9LA=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=MQtx6gBdR3HM9dh9ZSYyxZwJbM3nlPpVjcU436SduBYiu+PHwa4rHCJwvh9B8sC3r ESpuQ3s4HXlmZAuqzQLXjN3ySAcupbmfg2/kSlv8zjjetzTjhFqbGBQ1bm4cHPdTYF fr4UXFbbz2I1DMiBUPzkKoBMvySEI2D9Ny0A8Kx9YAj8NEx925cTN+DpDfkcebbxhz x7rFWEtl54/HYzcj03CEHwSTC3J/iAO/6sOS6ETCmCX3PFwbDF4nsg2N3F7sofS98k zm5n623yUddUlRnbrimwbIkZHcBgdvkPva8QL/bOCU9qWA8XvXzmzUuHwkqckbodAz XuYCyCB2KyC1w== Date: Mon, 13 Jul 2026 22:08:10 -1000 Message-ID: <241c12f5ce1fa4b60ac3f08a3518d4dc@kernel.org> From: Tejun Heo To: Andrea Righi Cc: David Vernet , Changwoo Min , sched-ext@lists.linux.dev, Emil Tsalapatis , linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 sched_ext/for-7.3 18/33] sched_ext: Add reject DSQ for cap-rejected dispatches In-Reply-To: References: <20260709225041.1695495-1-tj@kernel.org> <20260709225041.1695495-19-tj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Hello, Andrea. On Tue, Jul 14, 2026 at 08:49:49AM +0200, Andrea Righi wrote: > With CONFIG_EXT_SUB_SCHED=y, this calls scx_local_or_reject_dsq() for every > local DSQ insertion even when there are no sub-schedulers attached. It shouldn't > be too bad, but the hot path still pays for the out-of-line call and the > CID/capability bookkeeping. > > Maybe the same static key that I suggested for the ops.update_idle() case > (PATCH 28/33) can be used here as well and we could do something like: > > if (!static_branch_unlikely(&scx_has_sub_scheds)) > return &rq->scx.local_dsq; Yeah, this and the other sub-sched hot paths will be gated behind the static key in follow-up patches. Thanks. -- tejun