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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 50E33C433F5 for ; Sat, 28 May 2022 14:25:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236112AbiE1OZF (ORCPT ); Sat, 28 May 2022 10:25:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44624 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235857AbiE1OZF (ORCPT ); Sat, 28 May 2022 10:25:05 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61E091834B; Sat, 28 May 2022 07:25:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=3n7OczS1PtetK1QFTtWOYHDzv4XhdHqp3jM8IwjXG8U=; b=tTg6UwcV3Su/y3ILUPGeurwJEV viPkR2YPdjqbEN100npodPR4sEr6UPd7Oqd+XzBZs+wi0+cPWks3IN222rD02IrC836oczmsLAvVK jbpoBXAfTfiRvefseGe6TCmt1PBcl3CJsbTNKaGSh2jOHkDuygAOTIAlbHmanrksO/lgr0xEw/daX RafXWo+0rCRYJlegaXDjq0RTRcyGo+z6ATe1RwSuGuFEWHPXXewYsD5f/bkSyErLbQTJTPX/XloSu iDubEkqSkkTPzti2NVI3yqst12vbT8lz8W5l+ELn1RURxNI+B+jNTGVyehdvOo1s3HCy9G39fUzMD MRxYMlCg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nuxN7-002uyS-Ak; Sat, 28 May 2022 14:24:53 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 579DF3002A6; Sat, 28 May 2022 16:24:51 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id B598820289D16; Sat, 28 May 2022 16:24:50 +0200 (CEST) Date: Sat, 28 May 2022 16:24:50 +0200 From: Peter Zijlstra To: Juri Lelli Cc: Tejun Heo , Waiman Long , Frederic Weisbecker , LKML , "Paul E . McKenney" , Paul Gortmaker , Johannes Weiner , Marcelo Tosatti , Phil Auld , Zefan Li , Daniel Bristot de Oliveira , Nicolas Saenz Julienne , rcu@vger.kernel.org Subject: Re: [RFC PATCH 4/4] cpuset: Support RCU-NOCB toggle on v2 root partitions Message-ID: References: <20220525221055.1152307-1-frederic@kernel.org> <20220525221055.1152307-5-frederic@kernel.org> <20220526225141.GA1214445@lothringen> <9e44bb00-955a-dbc6-a863-be649e0c701f@redhat.com> <20220527083018.n43nc73vuuzm5ixo@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220527083018.n43nc73vuuzm5ixo@localhost.localdomain> Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Fri, May 27, 2022 at 10:30:18AM +0200, Juri Lelli wrote: > Hi, > > On 26/05/22 14:37, Tejun Heo wrote: > > On Thu, May 26, 2022 at 08:28:43PM -0400, Waiman Long wrote: > > > I am thinking along the line that it will not be hierarchical. However, > > > cpuset can be useful if we want to have multiple isolated partitions > > > underneath the top cpuset with different isolation attributes, but no more > > > sub-isolated partition with sub-attributes underneath them. IOW, we can only > > > set them at the first level under top_cpuset. Will that be useful? > > > > At that point, I'd just prefer to have it under /proc or /sys. > > FWIW, I was under the impression that this would nicely fit along the > side of other feaures towards implenting dynamic isolation of CPUs (say > https://lore.kernel.org/lkml/20220510153413.400020-1-longman@redhat.com/ > for example). Wouldn't be awkward to have to poke different places to > achieve isolation at runtime? This, that's what I was thinking. My main objection to the whole thing is that it's an RCU_NOCB specific interface. *That* I think is daft. I was thinking a partition would be able to designate a house-keeping sub-partition/mask, but who cares about all the various different housekeeping parties.