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 E3BEEC32774 for ; Fri, 19 Aug 2022 14:28:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231866AbiHSO2y (ORCPT ); Fri, 19 Aug 2022 10:28:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231433AbiHSO2u (ORCPT ); Fri, 19 Aug 2022 10:28:50 -0400 Received: from smtp-relay-canonical-0.canonical.com (smtp-relay-canonical-0.canonical.com [185.125.188.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5BB326123; Fri, 19 Aug 2022 07:28:48 -0700 (PDT) Received: from [10.172.66.188] (1.general.jsalisbury.us.vpn [10.172.66.188]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-canonical-0.canonical.com (Postfix) with ESMTPSA id C7D503F131; Fri, 19 Aug 2022 14:28:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1660919326; bh=jX/B2ux5/uBy+wzYzZZpmZkCJnX1pejB4rk9LuMf2Co=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=eXTYlHcxYaMv7YYKKK/pWWQxzFlg5AS34Q/Zu+mEmLwKItAuRGJWx00JuLbmQaGRU Y5Y2VpYws7Do9CdL8a7ZMfpSgK+gDlOlklk5Pz7aESNERyZydDDPn0zJ0WUgfaW+xP ombpwvBIeXnfslvpo1dkcVl6DeQ2oS8YDrW9ggm9d10C05CQR1LueAdCv/DSGkxoXe 0dpnU0KV26WVyO6egH1TYuakhn+U4p5GSTecw49PGEFSDHooqRXeVZXC1+A+9Sw8s6 3+JKByzsf/Iu+K1QBfMA+gn77gFvxuGRDFL0F88dQGZ+SDXLM6gidLZooMyhdQJ+y7 wF8GzhyO8xymA== Message-ID: Date: Fri, 19 Aug 2022 10:28:44 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [RFC} Commit 8a99b6833c88 Moves Important Real-time Settings To DebugFS Content-Language: en-US From: Joseph Salisbury To: Peter Zijlstra Cc: linux-rt-users@vger.kernel.org, williams@redhat.com, bigeasy@linutronix.de, valentin.schneider@arm.com, linux-kernel@vger.kernel.org, Marcelo Cerri References: <9e6a7216-9cb9-cba4-f150-1a0eaf56353c@canonical.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/18/22 21:38, Joseph Salisbury wrote: > > > On 8/18/22 16:31, Peter Zijlstra wrote: >> On Thu, Aug 18, 2022 at 03:53:28PM -0400, Joseph Salisbury wrote: >>> Hello, >>> >>> Some Ubuntu users are using the tuned package with a 5.15.x based >>> real-time >>> kernel.  Tuned adjusts various sysctl options based on a specified >>> profile. >>> This userspace package has stopped working > 5.13 due to the following >>> commit: >>> >>> 8a99b6833c88 "(sched: Move SCHED_DEBUG sysctl to debugfs)" >>> >>> This commit moved some important real-time sysctl knobs to debugfs in >>> 5.13-rc1.  It also appears some of the sysctl options were not moved, >>> sched_min_granularity_ns, for example. >>> >>> I was hoping to get some feedback on how to approach this. Would >>> upstream >>> real-time consider accepting a patch to the 5.15 real-time patch set >>> that >>> reverts this commit?  Or a new patch that adds the sysctl settings >>> back? >>> Any other ideas or feedback would be appreciated! >> None of those knobs were available when SCHED_DEBUG=n, so relying on >> them is your error to begin with. > We have had SCHED_DEBUG=y while this kernel is in beta, so you are > correct.  I need to investigate a different approach. >> >> Secondly, real-time? Which if those values affects anything in >> SCHED_FIFO/RR/DEADLINE ? > I am in the process of understanding how tuned[0] works. Many users > have reported success using tuned.  One use case for tuned is to > assign isolated cores to real-time processes and then move managed > IRQs out of these isolated cores.  This can be done easily with tuned > (I will research if there are other options to suggest). However, > tuned is trying to set the affected values when enabling a profile, > such as the real-time profile (Tuned offers many profiles based on a > workload type). > > I will investigate further to answer your point of what in > SCHED_FIFO/RR/DEADLINE those values affect.  It could be those values > are not needed at all. The dependency on them might be left over from > some need that no longer exists. > > Thank you again for the feedback! > > [0] https://tuned-project.org/ > I also see that the github repo[0] is at version 2.19-rc1, and the version being testing is 2.15.  Many of the issues we see may already be resolved. I will find out how I can participate in the tuned community.  At a minimum, I can start with testing and bug fixes. Thanks again for your feedback, Peter.  And sorry for the noise. Thanks, Joe [0] https://github.com/redhat-performance/tuned