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 EA8492931D2; Fri, 14 Aug 2026 22:34:55 +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=1786746896; cv=none; b=NsKGlQS8d+JkT/p0mmcf35ZN5udp13LqcVxNB00hlq5LVgz3z0PNMzFWMpQZadJ3m9fBS1qykAQztzOa7L86zGnzVvjhYUKF2GQbKLIXvDP5mdCBgVz6QR9SZovJJibO9Rvt0LP58vZwGiXTVv1lSQdlGau+5y4uBPPIS9xlPrc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786746896; c=relaxed/simple; bh=Pr6JgasY8cdZc/CAIerO3IBccT8bZwH3cHh7qYHe3rk=; h=Date:Message-ID:From:To:Cc:In-Reply-To:References:Subject; b=Uc5di7fhaEOEiBvKeJyGOHUbAJ98zsP1fUh5+c3N051bRxAC3N/0TnVEAD/9IcpxGD+gO+6xgLyH4m+AlY0GNSRDQFdfn6bGDzDwAVX+asKDdMmzDHbG41jlQz9JfNP8RicnDi3ghdry19XulIEOMM4UUXZ0xgT0AtRRh/GKFRI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SyTPKPHs; 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="SyTPKPHs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E6AB1F000E9; Fri, 14 Aug 2026 22:34:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786746895; bh=gRScg7kTTKP5QC+mwsYqWg2jzuEN+O506rd/2vJ4gVA=; h=Date:From:To:Cc:In-Reply-To:References:Subject; b=SyTPKPHstUDRr9zG1f768/nbU1ybcRKv+WxlgkAqEK8poikvd5cyqFoxUClxYfCdK RhJsRHGLKgrBvI38aqR+5PrcpkCzNZLKYwyQVDtn4Dk8NHmGMMZbB5yLeH800eIEZj gZWPtolneWKyt6rorouXjcSkMzIfail22r5sJxeAGMYUcMDNoCdXG/LQG/SG3AhPTT Cj9oInFMQjzJv+xbirXH/iukWRNkGZpv4y+xKpOXVMI9nV5z5zMJDKRJM2LkWI9FhO r8drhVIqXd3HkVoxMV8OF3h2kEBCwnrIDzpJjVJvoretp8x0eypT9z0MsoZkX3XJmq +IPcrF8YgHTMg== Date: Fri, 14 Aug 2026 12:34:54 -1000 Message-ID: <9a87b991e47916a87c00c1277e00066d@kernel.org> From: Tejun Heo To: Michal Blaszczyk Cc: David Vernet , Andrea Righi , Changwoo Min , sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org In-Reply-To: <20260811141358.2767765-1-michalblk@google.com> References: <20260811141358.2767765-1-michalblk@google.com> Subject: Re: [PATCH] selftests/sched_ext: Fix flaky ddsp failure tests on busy systems Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: On Tue, Aug 11, 2026 at 02:13:58PM +0000, Michal Blaszczyk wrote: > The ddsp_vtimelocal_fail and ddsp_bogus_dsq_fail tests skip calling > scx_bpf_dsq_insert_vtime() if scx_bpf_pick_idle_cpu() fails to find > an idle CPU (returns -1). On loaded systems, this results in the tests > skipping the very assertions they are meant to verify. > > Eliminate this flakiness by falling back to prev_cpu if no idle CPU is > found, ensuring the illegal dispatch operations are unconditionally > attempted and tested. Applied to sched_ext/for-7.3 with the description updated to say that scx_bpf_pick_idle_cpu() returns a negative error code on failure rather than -1. Thanks. -- tejun