From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay4-d.mail.gandi.net (relay4-d.mail.gandi.net [217.70.183.196]) (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 7DA422FF15B for ; Wed, 6 May 2026 07:41:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.183.196 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778053264; cv=none; b=ZHZJDm9fASORhO6faGPErC3jse3w8+tdUIuBB3EcZyQY2n7OtKMLdYq5xQC5tIVla6TMQyaB03r5uSAGOL/OkwOSrfDc7pYgEH8PtMuubSv12SrQ3U/el+tA1A11JbzLTIsVgkDAlYeygcRQK37y19RJNd372ug5D7IoikCKiIo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778053264; c=relaxed/simple; bh=m53RBzW9HKI4Ak55UrG2d7C3vGOJ/Kq5RPrbdfOGt6c=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=nR7fTmz5KVDW68bNbY9QDOYw8mj+/ojkjMXOjIVBcZYLMzAfccQm8Q64pMloKaLH76YZ1v0t0pHEY8UMJGHx/L2oqOxhbAkfkQewFCh2LA4a2499N/1ZXyA6vVhriQH4vPIuHr0k1qZ5tvrMMLWv7SfFpI5exa7tpGNzRvZ0VSg= 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=YBRmN/FO; arc=none smtp.client-ip=217.70.183.196 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="YBRmN/FO" Received: by mail.gandi.net (Postfix) with ESMTPSA id 208E63EE88; Wed, 6 May 2026 07:40:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=xenomai.org; s=gm1; t=1778053259; 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=CZFUz1bOGssynNSHPmtqafZIBbz0dNZgD5ATQpe+ClQ=; b=YBRmN/FOv9Bw1fa0tn3iP5cBh0V7CsjTEdtCoBIywZPEGWblJCNCbmslqrS4kdwL2aL8P/ z3lNO7Uh+yMyW4NAKC+rXBTUMQwR/pSCtuiLmjRZFe8wHBe+I7kDHgJ+KKLdimBCdfWKBD Ikc8ZBX9T4AJYeRYDEGrKB+MCoYl2DP6RrXhxLp262F1HQ4Ji4xG9nMo40KuWn6X8s6t2y PsWq603mPA3GxSZFaRNO6IFJ7Iqxo4ZwTdn0cjpJDnwenbyCnJvoUHz5Ea1CzWNcPb8vGn SAe0b3DRVOiXPDkTZqf3WZlENPYgot0X0uriEn21SmlltRbyp3F5eC/YL4LdkA== From: Philippe Gerum To: Jay Sridharan Cc: Brandon Ho , brho@relativityspace.com, jsridharan@relativityspace.com, xenomai@lists.linux.dev Subject: Re: Minor page faults from memory compaction causing in-band transitions In-Reply-To: (Jay Sridharan's message of "Mon, 4 May 2026 10:52:04 -0700") References: User-Agent: mu4e 1.12.12; emacs 30.2 Date: Wed, 06 May 2026 09:40:52 +0200 Message-ID: <87ecjpj88r.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 X-GND-Sasl: rpm@xenomai.org X-GND-State: clean X-GND-Score: -100 X-GND-Cause: 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 Hi Jay, Looks good to me, very useful for understanding some of the intricacies of virtual memory management vs real-time workloads, and how to address them. I would happily merge a commit with this information as-is. [I noticed a couple of hiccups breaking the patch format likely due to the MUA]. Jay Sridharan writes: > Hi Phillipe, > > Let me know what you think of this patch for the docs: > > diff --git a/content/core/caveat.md b/content/core/caveat.md > index b24e270..e11d605 100644 > --- a/content/core/caveat.md > +++ b/content/core/caveat.md > @@ -70,6 +70,68 @@ which depend on instrumenting the spinlock constructs (e.g. > `CONFIG_DEBUG_PREEMPT`), you may want to disable all the related kernel > options, starting with `CONFIG_SMP`. > > +### Memory compaction and page migration impact real-time behavior > {#caveat-memory-compaction} > + > +- Launch EVL threads. At the end of initialization, but before > calling mlockall.. -- Philippe.