From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from serv15.avernis.de (serv15.avernis.de [176.9.89.163]) (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 3C2403FBEC4 for ; Mon, 11 May 2026 14:13:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=176.9.89.163 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778508798; cv=none; b=gm3Z0kRcZNAZKf3Meqsc+yxdi4KWbghxWHBBJXvEcddzrmrrXUlI5ssZ77/5KoGn63WvRz8ATSdTxqwlWHvunad454vZd5qAmxi0b8Bgw2GzE0Yy10J4yHRWtYTLLWQSd50r9RsODWDeybV0NGcfZWmy5FIJqMU9mpl+dwSPBk4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778508798; c=relaxed/simple; bh=GgUrn5jnySBPCJ3qkw6gDMMO3cuuIe2bNUVYN50pAks=; h=MIME-Version:Date:From:To:Cc:Subject:In-Reply-To:References: Message-ID:Content-Type; b=G10w+4d0QT5Slh6PQgLfePlsJBz7FoIapOxAJzUpazwjGN1jSK07orHCn7NZHAYDqTuSNSpGFTURqzYKVfzNvkX6yuT0OgRGcnPXm3Wfm+Y8AjTkaFGU0hh0zSLA+aSjSe1MoxNwD297u0kZIiC6ao7Tmff0tgezyh+pWqz8Xaw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=umbiko.net; spf=none smtp.mailfrom=umbiko.net; dkim=pass (1024-bit key) header.d=umbiko.net header.i=@umbiko.net header.b=jJW4xt5e; arc=none smtp.client-ip=176.9.89.163 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=umbiko.net Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=umbiko.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=umbiko.net header.i=@umbiko.net header.b="jJW4xt5e" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=umbiko.net; s=mail; t=1778508793; bh=GgUrn5jnySBPCJ3qkw6gDMMO3cuuIe2bNUVYN50pAks=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=jJW4xt5ebkYQFBXysnEKDLB/7wX+b1oi1eDNL91DvRAeKpFZEh9c1PuOuR+F3OK/o 0NTdWRPemFtCyPvBgihgIdumBLZfyoTowZr6YNihQrV6iDbkTA0IWXBwZc/l79eTt2 k7ZIkVFwCm76bGkRaXD5kU44x8jQu81TkcvYIbzQ= Received: by serv15.avernis.de (Postfix) with ESMTPSA id DC86FBDEC982; Mon, 11 May 2026 16:13:12 +0200 (CEST) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Mon, 11 May 2026 14:13:12 +0000 From: Andreas Ziegler To: Juri Lelli Cc: Peter Zijlstra , linux-kernel@vger.kernel.org Subject: Re: sched/deadline: Use revised wakeup rule for dl_server In-Reply-To: References: <496e4b3329fe258da9618b9f05b18fcf@umbiko.net> Message-ID: <1ad125a7403c09166920de4e004bfc6d@umbiko.net> X-Sender: br025@umbiko.net Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: clamav-milter 1.4.3 at serv15.avernis.de X-Virus-Status: Clean Hi Juri, On 2026-05-11 12:46, Juri Lelli wrote: > Hello, > > On 08/05/26 08:09, Andreas Ziegler wrote: >> Linux kernel version: 6.12 >> CONFIG_PREEMPT_RT (w/ PREEMPT_RT patch applied) >> Architecture: aarch64 >> Platform: Raspberry Pi 4 >> >> Hi everyone, >> >> Commit d66792919d4f (sched/deadline: Use revised wakeup rule for >> dl_server) >> [1] introduced a marked degradation in scheduling latency for >> real-time >> tasks in the presence of heavy I/O load. > > Can this be the same regression reported here? > > https://marc.info/?l=linux-rt-users&m=177844667227991 Yes, this is the same issue. I wonder where the 50 ms are coming from ... The value is fairly consistent also in my results. > Please notice the list of missing subsequent fixes Mike is suggesting > to > test with. > > https://marc.info/?l=linux-rt-users&m=177847863710263&w=2 I will take a look at the mentioned patches. > Thanks, > Juri Thank you for the update, Andreas