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 55F6EC61DA4 for ; Thu, 23 Feb 2023 14:38:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234344AbjBWOiU (ORCPT ); Thu, 23 Feb 2023 09:38:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234824AbjBWOiT (ORCPT ); Thu, 23 Feb 2023 09:38:19 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 877973756E for ; Thu, 23 Feb 2023 06:38:16 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6F74161721 for ; Thu, 23 Feb 2023 14:38:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99E28C4339B; Thu, 23 Feb 2023 14:38:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677163095; bh=Il5cjRyZhP18Kl7YzTow8Y4DtM1TavqH9/R2keClECY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=iYTOfDSPYhIrnYskp0jSFs8uN6i0X+WahaU+X2Beia1FILupOn2o6gKKjwTMocRJ2 2//gc336+Qwp9qkFDDvBHu2TNusTnWzE2isC1o0x0bRUWE3f7BucoHP7d9zoLFvZYq 8zfUh2VyCdKUYsZZMCEREjEAUOns+KZMhYC6IaOLqjTkUWYXVoshVp2Ilr1Z4r+gvk XlwrZHWly5Gh/4ya0mrAgWM7S1a/Qu9n/vEBU5JdpjARtG1AHyTrmrk9h7IP5sVspV QwLPdrXZJdxV0q0XccFh4XelZNOL+56dywvtqsyTyiKYVRN4NJJAjc1QYQvOlaIQc4 KifhtgSz+eB1g== Message-ID: <05d03252-8190-4612-090c-b2a65c2523e3@kernel.org> Date: Thu, 23 Feb 2023 11:38:11 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Subject: Re: About rtla osnoise and timerlat usage To: Prasad Pandit Cc: linux-trace-users@vger.kernel.org References: <8ae9144f-6d7c-2b63-4fe7-4f124b5515bf@kernel.org> Content-Language: en-US From: Daniel Bristot de Oliveira In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-users@vger.kernel.org On 2/23/23 09:12, Prasad Pandit wrote: > Hello Daniel, > > On Thu, 23 Feb 2023 at 00:41, Prasad Pandit wrote: >> # trace-cmd record -p nop -e all -M 0x7FE -m 32000 --poll ~test/rt-tests/oslat --cpu-list 1-10 --duration 1h -w memmove -m 4K -T20 >> .... >> Maximum: 14 11 13 12 12 13 12 11 12 10 (us) >> Max-Min: 13 10 12 11 11 12 11 10 11 9 (us) >> Duration: 3599.986 3599.986 3599.987 3599.987 3599.986 3599.987 3599.986 3599.987 3599.986 3599.986 (sec) >> >> * Running oslat(1) with SCHED_OTHER priority via 'trace-cmd --poll' option, did not show the spike. Nonetheless, trace-cmd(1) logs show , ktimers/ and kworker/ threads running on isolated CPUs. >> * Now running rtla-osnoise(1) test with SCHED_OTHER: >> # rtla osnoise top -c 1-10 -d 6h -s 20 -T 20 -Po:0 -q -t > > Please see: > -> https://0bin.net/paste/ShXHmdvu#D0XY-WxTKCzWTxgQ+lTFbx1nB2TP2w+T0Mp8PBXt9gu > > * rtla-osnoise(1) running for 6 hours with SCHED_OTHER and SCHED_FIFO, > both did not report any spike above 20us. Good! > It's reporting occurrence of IRQs only, all other noise columns are > zero(0). That's a little surprising!? Regarding the IRQs only: That is a good sign! your isolation is good! Regarding the numbers: -T 20 is saying to the tracer to account as noise only noise >= 20 us. As you did not hit a single case as your -s20 did not stop the trace, that is expected. But I think that what you want is -T 1. That is, consider a noise anything that is > than 1 us. This will show you the noise added by those IRQs. Anyways, the isolation is good enough to have good numbers with SCHED_OTHER... without risks of starvation. > Thank you. > --- > - Prasad >