From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0DE84C6FA8E for ; Thu, 2 Mar 2023 12:56:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 49AF06B0074; Thu, 2 Mar 2023 07:56:44 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 44B256B0075; Thu, 2 Mar 2023 07:56:44 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 339D86B0078; Thu, 2 Mar 2023 07:56:44 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 251CF6B0074 for ; Thu, 2 Mar 2023 07:56:44 -0500 (EST) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id EEC35407A1 for ; Thu, 2 Mar 2023 12:56:43 +0000 (UTC) X-FDA: 80523957486.04.B409280 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by imf25.hostedemail.com (Postfix) with ESMTP id 1F575A0015 for ; Thu, 2 Mar 2023 12:56:40 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=obAnjgZc; spf=pass (imf25.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.28 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1677761801; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=9dfdj+0VRA1atO5irS3WM17Vy2/MRKhULv8ZRzYg1B8=; b=5vKDMnys4l5TW2SR+wi5koKNMXoiYDa2EnppQC0T+PSGSL0qgsOxCmRalJ0SLqIz4SfJkQ bpdg4ie2mEjEUA2w+4wEHw/ZUs4vJLPAV+/roA83DbrJ/swwIghFKNieUrmhQqA26XhfYB X91y0zoShKq3A0EzX3RJc1C5zaU43bs= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=obAnjgZc; spf=pass (imf25.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.28 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1677761801; a=rsa-sha256; cv=none; b=brXKSw9Xfp8eeyvBTc6GstyyOyV7GGhlmUVU0aryxZSb2vio39whzOklx/usYG/fpPUEqN caUlSeGITnpfgECpLg4olmfdnP/CKoDm92+3NgBxv51bVnP0aB/Wx9PQPjSzDqOAt7Stlt FKtssAPFTY1TJmTJsdAbMw1FaA2+aDE= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 68AED21DA6; Thu, 2 Mar 2023 12:56:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1677761799; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=9dfdj+0VRA1atO5irS3WM17Vy2/MRKhULv8ZRzYg1B8=; b=obAnjgZcykCoUbbN6rN8SKlIpKGzcD1NSN1YK83PLumRG5PgrbmA/U6H+4pybKywOWd8SP LX4PO09z8ZWzd2sP1/uFyLeuFRQHYQjWv60IPVPnMwmmbogjKc7QG4UBUhTDSQMxG3hBrn pzwiLv0H0AUaIdaOdUeGuJsuBL7XeOk= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 3AD1F13349; Thu, 2 Mar 2023 12:56:39 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 1BfYCwedAGTAMAAAMHmgww (envelope-from ); Thu, 02 Mar 2023 12:56:39 +0000 Date: Thu, 2 Mar 2023 13:56:38 +0100 From: Michal Hocko To: Valentin Schneider Cc: Sebastian Andrzej Siewior , cgroups@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Johannes Weiner , Michal =?iso-8859-1?Q?Koutn=FD?= , Peter Zijlstra , Thomas Gleixner , Vladimir Davydov , Waiman Long , Roman Gushchin , Shakeel Butt Subject: Re: [PATCH v5 2/6] mm/memcg: Disable threshold event handlers on PREEMPT_RT Message-ID: References: <20220226204144.1008339-1-bigeasy@linutronix.de> <20220226204144.1008339-3-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: qnquoycge7sgaj6ucyjgn3a4hk9s8y45 X-Rspamd-Queue-Id: 1F575A0015 X-HE-Tag: 1677761800-430582 X-HE-Meta: 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 fiTCSf7V Pb834wSdKP7YOzG6G0dvpm7H/RMTvfJNBeiFyo3yS0IZ6aR6J6O1q9wPog8uGVEjhRU2SKV4fYyGQojkx2RK5HTtpRwxxF8dS7aTBvBYDCbwweMzSfblp5eRJEK9EZpFSGcW9mwYy1F5nd5p0iH+O84OQ14qI4maXYw9/D2wjG8eyQ+b6hHO8RDVKw4T5C9EhACl9oiNI1i7aDTdtspe3Wkq4n5UWP6KnalDVfD5TayRnkwZYIbNNIj7+F7gxr1UltADwk9VRN1sm0BnWnUC6qjOmQDE43MtxigT0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu 02-03-23 12:30:33, Valentin Schneider wrote: > On 02/03/23 12:24, Michal Hocko wrote: > > On Thu 02-03-23 10:18:31, Valentin Schneider wrote: > >> On 02/03/23 08:45, Michal Hocko wrote: > >> > On Wed 01-03-23 18:23:19, Valentin Schneider wrote: > > [...] > >> >> I want cgroupv1 to die as much as the next person, but in that specific > >> >> situation I kinda need cgroupv1 to behave somewhat sanely on RT with > >> >> threshold events :/ > >> > > >> > Could you expand on the usecase? > >> > > >> > >> In this case it's just some middleware leveraging memcontrol cgroups and > >> setting up callbacks for in-cgroup OOM events. This is a supported feature > >> in cgroupv2, so this isn't a problem of cgroupv1 vs cgroupv2 feature > >> parity, but rather one of being in a transitional phase where the > >> middleware itself hasn't fully migrated to using cgroupv2. > > > > How is this related to the RT kernel config? memcg OOM vs any RT > > assumptions do not really get along well AFAICT. > > > > Yep. AIUI the tasks actually relying on RT guarantees DTRT (at least > regarding memory allocations, or lack thereof), but other non-RT-reliant > tasks on other CPUs come and go, hence the memcg involvement. So are you suggesting that the RT kernel is used for mixed bag of workloads with RT and non RT assumptions? Is this really a reasonable and reliable setup? What I am trying to evaluate here is whether it makes sense to support and maintain a non-trivial code for something that might be working sub-optimally or even not working properly in some corner cases. The price for the maintenance is certainly not free. -- Michal Hocko SUSE Labs