From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay5-d.mail.gandi.net (relay5-d.mail.gandi.net [217.70.183.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 81C5C31DDB7 for ; Mon, 20 Oct 2025 14:01:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.183.197 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760968883; cv=none; b=TkxYYe53xB6ET6Q7jBjFzz6/5Hjelj8bx1cx3fbACAqpxPlfsiyzL6nuAoXGiOg+V8wFYLDJlPQYXLO7fbw4ZQEw3FBVSwiZWuvtzukkTjIDtB8SMi0MsculHJ5AABoBm2410MJHWOA+MgU+ocR1+EJOL73Pz9rBkYEHu1pwuss= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760968883; c=relaxed/simple; bh=ntXSCNGYX0a/iE+f1vGSEeA+9203zKvj4Wpwqqc6iMA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=dTTAO6/Zfn/9Xy/4dNZen+Tvi1b1tHF5gzpbWL6DPTv9zBounlJQ1bvFFs0E3sfGBY3wI2iCyCLp5xPpB9tTLoMJ/HrUrS2bIm/tY171R8eOY5levMOwtbJuJMP4dnOT0abl2UDlFt5peOYVoUjY9hJBBS8uhgwLiFRNsgBhpug= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xenomai.org; spf=pass smtp.mailfrom=xenomai.org; dkim=pass (2048-bit key) header.d=xenomai.org header.i=@xenomai.org header.b=bzFVaWTo; arc=none smtp.client-ip=217.70.183.197 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xenomai.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=xenomai.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=xenomai.org header.i=@xenomai.org header.b="bzFVaWTo" Received: by mail.gandi.net (Postfix) with ESMTPSA id C433C43A8E; Mon, 20 Oct 2025 14:01:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=xenomai.org; s=gm1; t=1760968873; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ntXSCNGYX0a/iE+f1vGSEeA+9203zKvj4Wpwqqc6iMA=; b=bzFVaWToW0Ef5/bTs+5Q5PGypSTrShPVW7iw5IDrTjoozeTbbTbQe8x4HPfFcKdVdiFDz6 R86mJoOJ1h051P+PbnBF9ViK4cERPpMUi0oFLMDilp5q9Q9ICjm47I0ytdvSgJFu6+mBg7 oV3fTJeCqjirw4GGEuXs6zeP7JnOrxbFfYLR90uH2MDTcMo+ssD0xL8MappPmxVgBbQjaa 1cH9Bgkk28hkHnY+e5Ko3yeEEAfKcCCRLJxXu3AKVbm3migi2i9/X0ynjs0wnrZbTZZjaM PjUXssjDrC9oW+AmU+m3ZF44IMTFG8Dd5GFsbyrK8xabQMkvYQlJ2BZ+oEEs4g== From: Philippe Gerum To: Giulio Moro Cc: =?utf-8?Q?=C5=81ukasz?= Majewski , Xenomai Subject: Re: Unexpected switches to in-band In-Reply-To: <9d2bacac-8d70-f083-e926-21beee2207c2@bela.io> (Giulio Moro's message of "Mon, 20 Oct 2025 07:46:10 -0500") References: <20251009151737.0d03b211@wsk> <20676160-4572-d92d-4b33-ff4255946345@bela.io> <87qzv9sa9c.fsf@xenomai.org> <87ikgls9kh.fsf@xenomai.org> <20251020094705.2ac256f2@wsk> <9d2bacac-8d70-f083-e926-21beee2207c2@bela.io> User-Agent: mu4e 1.12.12; emacs 30.2 Date: Mon, 20 Oct 2025 16:01:12 +0200 Message-ID: <87o6q1ad07.fsf@xenomai.org> Precedence: bulk X-Mailing-List: xenomai@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-GND-Sasl: rpm@xenomai.org Giulio Moro writes: > =C5=81ukasz Majewski wrote on 20/10/2025 02:47: > >> Could you share which version of libevl do you use? > > I was using the latest release of libevl that was compatible with the ker= nel UAPI. > Sorry I haven't provided more details on the issue; I am focusing on buil= ding an image around 6.1 for a deadline coming up next month so I haven't b= een able to get into tracing yet. > > The only additional finding I have so far is that there seems to be > something on the Linux side that "breaks real-time" which affects both > linux and evl. In the below list, "evl bad" means that the above > mentioned ISW are observed. "Linux bad" means that I see a > disproportionate number of underruns under stress on a Linux program > running with SCHED_FIFO and priority 95 with a period of 360us. I > understand "disproportionate" is a very subjective term but, to give > an idea, over a 10 minutes test I get a couple of underruns with > "linux good" and I get hundreds of underruns with "linux good" > > v6.12.y-evl-rebase: evl bad, linux bad > v6.11.y-evl-rebase: evl bad, linux untested > v6.10.y-evl-rebase: evl bad, linux untested > v6.9.y-evl-rebase: evl bad, linux bad > v6.6.y-evl-rebase: evl bad, linux bad > v6.3.y-evl-rebase: evl bad, linux bad on startup only > v6.2.y-evl-rebase: libevl r42, evl good, linux good > v6.1.y-cip-evl-rebase: libevl master, evl good, linux good > > Not sure if this is of any help; I hope to be able to get back on this so= on. > Best, > Giulio If someone could send me the relevant portion of a trace file with a 'latspot' tracepoint triggered on a latmus run, I could investigate this issue. I'd need the function tracer active on all CPUs, with all traces dumped to a single trace file ('evl trace -ef' should do). --=20 Philippe.