From patchwork Mon Aug 5 09:17:22 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Felix Moessbauer X-Patchwork-Id: 13753538 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 aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 87F85C52D6D for ; Mon, 5 Aug 2024 11:37:56 +0000 (UTC) Received: from mta-65-226.siemens.flowmailer.net (mta-65-226.siemens.flowmailer.net [185.136.65.226]) by mx.groups.io with SMTP id smtpd.web10.3992.1722849465879241674 for ; Mon, 05 Aug 2024 02:17:46 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=felix.moessbauer@siemens.com header.s=fm1 header.b=CmZn/1lo; spf=pass (domain: rts-flowmailer.siemens.com, ip: 185.136.65.226, mailfrom: fm-1321639-202408050917427ad3e329f0f9229c88-hmamui@rts-flowmailer.siemens.com) Received: by mta-65-226.siemens.flowmailer.net with ESMTPSA id 202408050917427ad3e329f0f9229c88 for ; Mon, 05 Aug 2024 11:17:43 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; s=fm1; d=siemens.com; i=felix.moessbauer@siemens.com; h=Date:From:Subject:To:Message-ID:MIME-Version:Content-Type:Content-Transfer-Encoding:Cc; bh=9qDzGPZK0KRNuwsuLLWsW7dMYyIlCrC1pgbePkPRT/A=; b=CmZn/1lowmcB5AOE0hyntWUfkAb59Sv59KVjsLxhq5x8eoBJCyq8b1l1fq6fwJEH6zr7CC BIOju0tSaOFTOICtEK33SnQODmrU3RuXBtP/WbdQsr+jS0oOasP6YkPiNPwsz11B7cXnpSsm PeB4f8BI4WVuLkkP0dug/PNDjTr2SnLJ+FJT/UhaNOSrowz4A5Fmna8z2UdXcd3kc/DJOztx oGhrUgvoSvgQReaFta4ya06c/ZM/SdFwY9U+3ND4mHK9ZGpkI7vv57Bx5g2Ea8M1mXtJdvnj j31PKuFlWkvG+0gBiVVJs1WPyWDkCIq9iYn86uCFA6y5WuaZJMgxNukw==; From: Felix Moessbauer To: cip-dev@lists.cip-project.org Cc: jan.kiszka@siemens.com, quirin.gylstorff@siemens.com, Felix Moessbauer Subject: [isar-cip-core][PATCH 1/1] fix(PREEMPT_RT): disable CONFIG_RT_GROUP_SCHED Date: Mon, 5 Aug 2024 11:17:22 +0200 Message-Id: <20240805091722.6871-1-felix.moessbauer@siemens.com> MIME-Version: 1.0 X-Flowmailer-Platform: Siemens Feedback-ID: 519:519-1321639:519-21489:flowmailer List-Id: X-Webhook-Received: from li982-79.members.linode.com [45.33.32.79] by aws-us-west-2-korg-lkml-1.web.codeaurora.org with HTTPS for ; Mon, 05 Aug 2024 11:37:56 -0000 X-Groupsio-URL: https://lists.cip-project.org/g/cip-dev/message/16715 This feature is simply broken on RT kernels that use cgroup2, as the cpu controller features rt_period_us and rt_runtime_us are not exposed, which are needed to configure things in a way that allows to run tasks under RT/DL scheduling policies. It further seems to be incompatible with the nohz_full option. This patch just disables the feature, similar to upstream Debian. Signed-off-by: Felix Moessbauer --- I'm wondering a bit how that was not discovered earlier in our RT tests. Maybe Quirin can have a look if the cyclictest also shows errors that the scheduling policy cannot be set. But maybe it simply did not show up there, as the setup was to simplistic and did not enable the cgroup2 cpu controller. Note: This was discovered while tracing down kernel bugs around timer slack on RT/DL tasks. Best regards, Felix Moessbauer Siemens AG recipes-kernel/linux/files/preempt-rt.cfg | 1 + 1 file changed, 1 insertion(+) diff --git a/recipes-kernel/linux/files/preempt-rt.cfg b/recipes-kernel/linux/files/preempt-rt.cfg index 4afe1bf..ea37556 100644 --- a/recipes-kernel/linux/files/preempt-rt.cfg +++ b/recipes-kernel/linux/files/preempt-rt.cfg @@ -1,6 +1,7 @@ # >= 5.10 CONFIG_EXPERT=y CONFIG_PREEMPT_RT=y +CONFIG_RT_GROUP_SCHED=n # <= 4.19 CONFIG_PREEMPT_RT_FULL=y