From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=193.142.43.55 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794565124; b=G1l6oUDvAdDm6FQewmQH5Ec5JR0j+KnM/5FdNlWAcDiHOEi/jFA4L6ggUEyUpcGm515a 8QiXvpswUjZIIKMbfup6GnaGt22iqPSwHW5vbEnJyE1aSyqhc8RAEsraoOpUR11v3lnE+ y+//ahOsixezW/TCRPljz2AV4ss04LEqked0wWtoQduv9dlUEQSb57GOOfTMJwO2X5vd+ ddZIwwJ18qPQmxq+MeXCVzDGCP0ZwoQ25y7fF2HRymXXkO2qxVnliaODzznfWlv/Av2EH hK7hD6+7LMp4mCv6ir4JRknjftsA26XzZJTYCxxEL7wGUag+OYlzAv59oR+EJ3fRYdg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794565124; h=DMARC-Filter:Date:DKIM-Signature:DKIM-Signature:From:To:Cc:Subject: Message-ID:References:MIME-Version:Content-Type:Content-Disposition: In-Reply-To; bh=GDqKLySI9xov4G2CrkoKgL3wsghKRx2H516sy7kfjC0=; b=1puuGT2un+Dyz2w4jquyi5kDmqy54Lsy9WCnIcOs3cYqZoKO1zFAaPH42/ERZ7/TeQqX El1AjsIytb0hqXEywF8PtX99kVCODwDF1GA2HOknwOL7xq1xUoPErhKKDIs9ZxoSrjLRU NYHcDRuTa6KLfWG5ih69uaJ7AmvEgF4kd3Ci5icWG7BmATlg84+JMgulYROxBoIgCpHs1 qesP0KIrDvWdB0UYbdlPIDItJL7yo6M4kFsOICc0txKn9KmSdaFd7Lqe0oiCRf3DDW1dY XM2AyyyKgEerkxohzadQfhbzUJLbKLO5iZOmTwBaxKk/iD6FfmYqEDjrdcDkxuWEDig== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b="AhH/5FHn"; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=RR0xxxl7; arc=none smtp.remote-ip=193.142.43.55 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E1BF4606A327 for ; Fri, 13 Nov 2026 10:18:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org E1BF4606A327 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b=AhH/5FHn; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=RR0xxxl7 Date: Fri, 13 Nov 2026 11:18:40 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1794565121; 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=GDqKLySI9xov4G2CrkoKgL3wsghKRx2H516sy7kfjC0=; b=AhH/5FHn0hpsvtbMWUtAzPXUo76KMllKJqFucagbH1xo3LX6MHr4sydVx/SK1VhsdMGNsz Vg3/hKoLSTYSfWIFWmCmEpYv2Ch4a4tRNuvwtBoJPe3g0oF+dyZPdc7nS/LkdNkoOuooqy nsuE/E0VYtdKVjmATk/PHWU0QoRau6J+ecw0wYbnNS53NuX40+tLUc74kZr7c/TWaga61o 3EUz/68ZObjCRAUotxfL+AbweiV1Wydjf7A0UMndq6S2w8hfQTX9gJdIl1+cc/ZHyNEt1m VFoXDh9SZyzfhccI56pbioyT518HvV/uX61xyHHeTfSevFvRZ0YiVTTJYYyZwQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1794565121; 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=GDqKLySI9xov4G2CrkoKgL3wsghKRx2H516sy7kfjC0=; b=RR0xxxl73/fRzzCMqAWNaGZk+qQQPoDluyYWFe1WR+xwHbN7Ynz+jKoYI3S+cUaE7IsvET SChbGaNukG1StyBQ== From: Sebastian Andrzej Siewior To: Tomas Glozar Cc: Daniel Wagner , Steven Rostedt , Clark Williams , linux-trace-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev Subject: Re: [PATCH] rtla/timerlat: Lock the memory of the user-space threads Message-ID: <20261113101840.26aMfOtJ@linutronix.de> References: <20261112-rtla-mlock-v1-1-418986711b20@monom.org> <20261113094423.xgAx5Goo@linutronix.de> X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On 2026-11-13 11:07:15 [+0100], Tomas Glozar wrote: > I agree, you are right. I was thinking about rtla setting > /dev/cpu_dma_latency to 0 as an option rather than by default (unlike > cyclictest, in that case). If rtla's idea is to measure the system in Oh, yes. cpu_dma_latency is tricky because of all that happens to a system setup and might not be expected and then people wonder why the system behaves differently if a certain application runs. mlock on the other hand is something clearly defined and explained why it is important. > its current configuration, it makes sense not to tune it by default. > But the rtla user thread not having mlockall is a misconfiguration of > the rtla thread (i,e. the measurement tool), not of the system. > > Plus, cyclictest can run as a non-root user that might not have > permissions to mlockall. That is not an issue with rtla, which always > runs as root. I don't think mlock is restricted to a root user. It might be that "huge" application might exceed their memory limit during mlock and "usually" their memory is just virtual and never faulted in. > So I take that back. mlockall by default is fine. Oki. > Tomas Sebastian