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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8BC21C433E0 for ; Mon, 22 Feb 2021 16:22:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E52A64E2F for ; Mon, 22 Feb 2021 16:22:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231688AbhBVQVv (ORCPT ); Mon, 22 Feb 2021 11:21:51 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:46292 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231598AbhBVQVX (ORCPT ); Mon, 22 Feb 2021 11:21:23 -0500 Date: Mon, 22 Feb 2021 17:20:35 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1614010836; h=from:from:reply-to:subject:subject: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=dMKGKwsQDejFqgv122do7LdXCQp31z5eR4/NXdM5Ids=; b=tvEDHvLxRQKOC5nDbLPUe9TBjRKvfdMQ1qvRdhWPjsoXg+rzFmNbVUtGXdALxTTBeTfbut CzqUDY3+BzKpYvcttgGOG7I7h5SBPTxAMUdggNFqFk+RmLTzZLTx+9mAKXbjhGbsRvAx+F Jk7hak49GWUMpvI/1HfHRwoJZj/b0bBrx1RoUnPe4jjfxxqx7+g5QgRCppAjNFuknlUXRU 0g6eTcGDb6NOO9ZSAIvtPSURXAnYnTjrMDDx1rxX55v92klfs4xU98XSG/j8EKgSZImqcl OTT1HfZdi6NaHrTV4TqswwqaXzu6FY+6PsYco0o9nhKT6N+67+ya8Uqr7kcb9Q== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1614010836; h=from:from:reply-to:subject:subject: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=dMKGKwsQDejFqgv122do7LdXCQp31z5eR4/NXdM5Ids=; b=uk3fIgdXML8vBovUeEmuuWrpdmE6k6PDXdmTOhtt+tixafw9AXnBG2Ysk0aYblf1COBOvC 52M2LOpvjfBSBWBw== From: "Ahmed S. Darwish" To: Jonathan Schwender Cc: jkacur@redhat.com, williams@redhat.com, linux-rt-users@vger.kernel.org Subject: Re: rt-tests: cyclictest: Add option to specify main pid affinity Message-ID: References: <20210222152833.8758-1-schwenderjonathan@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210222152833.8758-1-schwenderjonathan@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org On Mon, Feb 22, 2021 at 04:28:30PM +0100, Jonathan Schwender wrote: > > Hi John, > > This patch adds the option --mainaffinity to specify the affinity of > the main pid. > This is mainly useful if you want to bind the main thread to a > different (e.g. housekeeping ) CPU than the measurement threads. > Pardon my ignorance; can you please specify why is this important? The measurement threads have an RT priority while the main thread is SCHED_OTHER. So why would the cyclictest measurements really be affected by the main thread (unless there's a preempt_rt bug)? Do you also have any numbers showing different results with/without "--mainaffinity"? Thanks, -- Ahmed S. Darwish