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 548D0C433DB for ; Wed, 24 Mar 2021 09:33:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0530361A09 for ; Wed, 24 Mar 2021 09:33:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232306AbhCXJc7 (ORCPT ); Wed, 24 Mar 2021 05:32:59 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:39338 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231843AbhCXJco (ORCPT ); Wed, 24 Mar 2021 05:32:44 -0400 Date: Wed, 24 Mar 2021 10:32:39 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1616578363; 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=4kpIjaa/mmToGzBMdJSsSDMla3gynHsUQP6WFJr2IyM=; b=xK0mF3XlDAn3moLnQMmG4ejY2+fMcdQDE5sydDx+QO2MT6g+DtoIcC1r4YvTW4YGmg2Mym /PibNIJoF7gBvX18z50WS9k078Xn6ZbcVYTCchg1vlrBb41vv9AGmSf2rAcMyV0/ZmtKBx Sjf2bvc1t1tV3BbqEwjCbv3nlu7wM//XIr6eFzuDpZl8/Ehj5uoMhhS66x7wUNBAngRzE5 NArj41evBBsd50WTTT96SltTJsPiRMTqHAmYbzWXzn7PKBis+4LO4brarMDqFCaKxmvvTP 1F27HInkZ6EuW01BBJmkgvqpyiI7zVMxgYsn/9ttf39wSESzmydy4BjAYS/JzA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1616578363; 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=4kpIjaa/mmToGzBMdJSsSDMla3gynHsUQP6WFJr2IyM=; b=cM/yzJ7mOu3U9VBiDM2iu6UESfJS27DDIB5ryN4hK7oEn2gmeBIxs9eN0ou3fCj8p9GVHt TBMrV4xPE1/AQ2CA== 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: Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org Hi Jonathan, On Mar 21, 2021, Jonathan Schwender wrote: > > On 2/22/21 5:20 PM, Ahmed S. Darwish wrote: > > > > Do you also have any numbers showing different results > > with/without "--mainaffinity"? > > Sorry for the delay. I do have some numbers now, and there is a > benefit to using this option if CPU isolation + CAT are > used. Otherwise it's not really visible. > Thanks a lot for the results. Since I'm doing some CAT-related stuff on RT tasks vs. GPU workloads, I'm curious, how much was the benefit of CAT ON/OFF? In your benchmarks you show that the combination of --mainaffinity, CPU isolation, and CAT, improves worst case latency by 2 micro seconds. If you keep everything as-is, but disable only CAT, how much change happens in the results? Also, how many classes of service (CLOS) your CPU has? How was the cache bitmask divided vis-a-vis the available CLOSes? And did you assign isolated CPUs to one CLOS, and non-isolated CPUs to a different CLOS? Or was the division more granular? Kind regards, -- Ahmed S. Darwish Linutronix GmbH