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 EFD6C25E451; Thu, 14 Aug 2025 08:37:25 +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=1755160646; cv=none; b=h664XuTqnHu7GYpfmAUiMALDUkSKwD5KnSUj5Dvn+6wftdSsm+snnhtHjSTPJS+haIsayoivcCHfz9CfKkNmBn8bCRLpQeKcrC99lFsu4+iaxNQEV8tCQjJNsS0mOPWC7UdhaV6GSA3uv5+cnPgmVaGvtm2LIswFYoZbERWN7Xw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755160646; c=relaxed/simple; bh=4hgYOboBwr07GDnqTowvvQ/VZ9PXOaAt8FWiNkvyJSA=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=KVyCmz2ZSmh//3bG9W684yIUFTU2jIIB0WRjgFnwtJuDL0KfXR75aUXE1caJTaifYLdMLD0CLXk0wXwsGlG9VOXUggeoUiumFZcTQgGqA1rK9bixzy0nI+g58/U9ObiVZv8rKICnRDXxqDXbR0XKkNV2PxpBHOz+2dRFl6JRSLk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LBkRtPkN; 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="LBkRtPkN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0B2BFC4CEF4; Thu, 14 Aug 2025 08:37:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755160645; bh=4hgYOboBwr07GDnqTowvvQ/VZ9PXOaAt8FWiNkvyJSA=; h=Date:Subject:From:To:Cc:References:In-Reply-To:From; b=LBkRtPkNu0IlnWkQ9WyQvaOneSBW8OHUVGBEG7za+2z0PDUYOyuMnyUSBpTFHYIOt MR2Ib9v3nXyLzMu9srkdAp0CMu3haoI6fthZpJOEjBfB4uEydrRYSQf3T93q7jUdbG 7QlUS/U5YyzfrAWcLzHZkizO44ev5svISjofIhXqnsVXvq0njRcJv4eMIXnRa7brPb 1f3Bteh30883M24nC/KlJ27tkxqkozT9dIuo210He02a8VWQaRMQZCfIsnGGoteguN +M/dUWbTwfCxOOyEbOuNADOVRe1GZHRsH1vY7357fKAekjSdfcFPA64MPXGOESguYQ sOjIEpY/hWXLA== Message-ID: <58c46200-95b0-4cd8-bb5e-44f963a66875@kernel.org> Date: Thu, 14 Aug 2025 10:37:22 +0200 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 6.16 199/627] sched/deadline: Less agressive dl_server handling From: Jiri Slaby To: Greg Kroah-Hartman , stable@vger.kernel.org Cc: patches@lists.linux.dev, Chris Mason , "Peter Zijlstra (Intel)" , Juri Lelli , Sasha Levin References: <20250812173419.303046420@linuxfoundation.org> <20250812173426.853672780@linuxfoundation.org> <17955c87-1a82-4eae-94ee-3ac1447d4e71@kernel.org> Content-Language: en-US Autocrypt: addr=jirislaby@kernel.org; keydata= xsFNBE6S54YBEACzzjLwDUbU5elY4GTg/NdotjA0jyyJtYI86wdKraekbNE0bC4zV+ryvH4j rrcDwGs6tFVrAHvdHeIdI07s1iIx5R/ndcHwt4fvI8CL5PzPmn5J+h0WERR5rFprRh6axhOk rSD5CwQl19fm4AJCS6A9GJtOoiLpWn2/IbogPc71jQVrupZYYx51rAaHZ0D2KYK/uhfc6neJ i0WqPlbtIlIrpvWxckucNu6ZwXjFY0f3qIRg3Vqh5QxPkojGsq9tXVFVLEkSVz6FoqCHrUTx wr+aw6qqQVgvT/McQtsI0S66uIkQjzPUrgAEtWUv76rM4ekqL9stHyvTGw0Fjsualwb0Gwdx ReTZzMgheAyoy/umIOKrSEpWouVoBt5FFSZUyjuDdlPPYyPav+hpI6ggmCTld3u2hyiHji2H cDpcLM2LMhlHBipu80s9anNeZhCANDhbC5E+NZmuwgzHBcan8WC7xsPXPaiZSIm7TKaVoOcL 9tE5aN3jQmIlrT7ZUX52Ff/hSdx/JKDP3YMNtt4B0cH6ejIjtqTd+Ge8sSttsnNM0CQUkXps w98jwz+Lxw/bKMr3NSnnFpUZaxwji3BC9vYyxKMAwNelBCHEgS/OAa3EJoTfuYOK6wT6nadm YqYjwYbZE5V/SwzMbpWu7Jwlvuwyfo5mh7w5iMfnZE+vHFwp/wARAQABzSFKaXJpIFNsYWJ5 IDxqaXJpc2xhYnlAa2VybmVsLm9yZz7CwXcEEwEIACEFAlW3RUwCGwMFCwkIBwIGFQgJCgsC BBYCAwECHgECF4AACgkQvSWxBAa0cEnVTg//TQpdIAr8Tn0VAeUjdVIH9XCFw+cPSU+zMSCH eCZoA/N6gitEcnvHoFVVM7b3hK2HgoFUNbmYC0RdcSc80pOF5gCnACSP9XWHGWzeKCARRcQR 4s5YD8I4VV5hqXcKo2DFAtIOVbHDW+0okOzcecdasCakUTr7s2fXz97uuoc2gIBB7bmHUGAH XQXHvdnCLjDjR+eJN+zrtbqZKYSfj89s/ZHn5Slug6w8qOPT1sVNGG+eWPlc5s7XYhT9z66E l5C0rG35JE4PhC+tl7BaE5IwjJlBMHf/cMJxNHAYoQ1hWQCKOfMDQ6bsEr++kGUCbHkrEFwD UVA72iLnnnlZCMevwE4hc0zVhseWhPc/KMYObU1sDGqaCesRLkE3tiE7X2cikmj/qH0CoMWe gjnwnQ2qVJcaPSzJ4QITvchEQ+tbuVAyvn9H+9MkdT7b7b2OaqYsUP8rn/2k1Td5zknUz7iF oJ0Z9wPTl6tDfF8phaMIPISYrhceVOIoL+rWfaikhBulZTIT5ihieY9nQOw6vhOfWkYvv0Dl o4GRnb2ybPQpfEs7WtetOsUgiUbfljTgILFw3CsPW8JESOGQc0Pv8ieznIighqPPFz9g+zSu Ss/rpcsqag5n9rQp/H3WW5zKUpeYcKGaPDp/vSUovMcjp8USIhzBBrmI7UWAtuedG9prjqfO wU0ETpLnhgEQAM+cDWLL+Wvc9cLhA2OXZ/gMmu7NbYKjfth1UyOuBd5emIO+d4RfFM02XFTI t4MxwhAryhsKQQcA4iQNldkbyeviYrPKWjLTjRXT5cD2lpWzr+Jx7mX7InV5JOz1Qq+P+nJW YIBjUKhI03ux89p58CYil24Zpyn2F5cX7U+inY8lJIBwLPBnc9Z0An/DVnUOD+0wIcYVnZAK DiIXODkGqTg3fhZwbbi+KAhtHPFM2fGw2VTUf62IHzV+eBSnamzPOBc1XsJYKRo3FHNeLuS8 f4wUe7bWb9O66PPFK/RkeqNX6akkFBf9VfrZ1rTEKAyJ2uqf1EI1olYnENk4+00IBa+BavGQ 8UW9dGW3nbPrfuOV5UUvbnsSQwj67pSdrBQqilr5N/5H9z7VCDQ0dhuJNtvDSlTf2iUFBqgk 3smln31PUYiVPrMP0V4ja0i9qtO/TB01rTfTyXTRtqz53qO5dGsYiliJO5aUmh8swVpotgK4 /57h3zGsaXO9PGgnnAdqeKVITaFTLY1ISg+Ptb4KoliiOjrBMmQUSJVtkUXMrCMCeuPDGHo7 39Xc75lcHlGuM3yEB//htKjyprbLeLf1y4xPyTeeF5zg/0ztRZNKZicgEmxyUNBHHnBKHQxz 1j+mzH0HjZZtXjGu2KLJ18G07q0fpz2ZPk2D53Ww39VNI/J9ABEBAAHCwV8EGAECAAkFAk6S 54YCGwwACgkQvSWxBAa0cEk3tRAAgO+DFpbyIa4RlnfpcW17AfnpZi9VR5+zr496n2jH/1ld wRO/S+QNSA8qdABqMb9WI4BNaoANgcg0AS429Mq0taaWKkAjkkGAT7mD1Q5PiLr06Y/+Kzdr 90eUVneqM2TUQQbK+Kh7JwmGVrRGNqQrDk+gRNvKnGwFNeTkTKtJ0P8jYd7P1gZb9Fwj9YLx jhn/sVIhNmEBLBoI7PL+9fbILqJPHgAwW35rpnq4f/EYTykbk1sa13Tav6btJ+4QOgbcezWI wZ5w/JVfEJW9JXp3BFAVzRQ5nVrrLDAJZ8Y5ioWcm99JtSIIxXxt9FJaGc1Bgsi5K/+dyTKL wLMJgiBzbVx8G+fCJJ9YtlNOPWhbKPlrQ8+AY52Aagi9WNhe6XfJdh5g6ptiOILm330mkR4g W6nEgZVyIyTq3ekOuruftWL99qpP5zi+eNrMmLRQx9iecDNgFr342R9bTDlb1TLuRb+/tJ98 f/bIWIr0cqQmqQ33FgRhrG1+Xml6UXyJ2jExmlO8JljuOGeXYh6ZkIEyzqzffzBLXZCujlYQ DFXpyMNVJ2ZwPmX2mWEoYuaBU0JN7wM+/zWgOf2zRwhEuD3A2cO2PxoiIfyUEfB9SSmffaK/ S4xXoB6wvGENZ85Hg37C7WDNdaAt6Xh2uQIly5grkgvWppkNy4ZHxE+jeNsU7tg= In-Reply-To: <17955c87-1a82-4eae-94ee-3ac1447d4e71@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 14. 08. 25, 10:22, Jiri Slaby wrote: > Hi, > > > On 12. 08. 25, 19:28, Greg Kroah-Hartman wrote: >> 6.16-stable review patch.  If anyone has any objections, please let me >> know. >> >> ------------------ >> >> From: Peter Zijlstra >> >> [ Upstream commit cccb45d7c4295bbfeba616582d0249f2d21e6df5 ] >> >> Chris reported that commit 5f6bd380c7bd ("sched/rt: Remove default >> bandwidth control") caused a significant dip in his favourite >> benchmark of the day. Simply disabling dl_server cured things. >> >> His workload hammers the 0->1, 1->0 transitions, and the >> dl_server_{start,stop}() overhead kills it -- fairly obviously a bad >> idea in hind sight and all that. >> >> Change things around to only disable the dl_server when there has not >> been a fair task around for a whole period. Since the default period >> is 1 second, this ensures the benchmark never trips this, overhead >> gone. > > This causes: > sched: DL replenish lagged too much > > Maybe some prereq missing? Not really, this is present both in linus/master and tip/master. >> Fixes: 557a6bfc662c ("sched/fair: Add trivial fair server") >> Reported-by: Chris Mason >> Signed-off-by: Peter Zijlstra (Intel) >> Reviewed-by: Juri Lelli >> Acked-by: Juri Lelli >> Link: https://lkml.kernel.org/r/20250702121158.465086194@infradead.org >> Signed-off-by: Sasha Levin > > thanks, -- js suse labs