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=1794586660; b=5Si1diTDRxwkWsbIqmRTV8WdP2vJ6ywpd4qZdri6oSnj5SHpl2WfmfGcscTKMQE4UGeY XqdjQ+I4tJNcV+1AmHmtddPnOHFYYLl9X7DsOfsmPJt+d9oBQ4Fgn3DSsK0dobSEly1Br cOR1R7hf2/A8SeEPuHL9vcAOcTeLHaVyKeE4FkoQIVYLj6rSqE2eDZNFnQpWwLCe+yraH WilIja+mjMaepRJdr7+w9s7agELEffbeIBFui0wWxn9Adk8XOsbB/xrUsMc3wEBugyg08 pFCyd3VAB1hCnIkllAN3Oc8x6sPCDaJxAYLpx6nnAgyo2ohNTPWRF/XGGiHvdURnj4g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794586660; h=DMARC-Filter:From:DKIM-Signature:DKIM-Signature:To:Cc:Subject: In-Reply-To:References:Date:Message-ID:MIME-Version:Content-Type; bh=YmKdqa9PN50e2UkKt3EfBiqD0YdHB3OU7Jqo14mmKwc=; b=qF1DRkqf3st+npOWMAchyRugZDilP8icWyD7ORZ1noLoxqSS7l2VMnYuIbC76ihPg52I Ga70C7MmOVO2CpH6Q9FuNed82yYkmARuFjkcV1lQOY+kB8T8ccUjs08eakBzls7FfT8L6 nANXXHiRwlP9oSfNSMQ8SwSTBTnTAhIax3XXP+A8+8vwCblC9wdPYsN7H2iglyS6DHzPJ 9ljep0A8Yy8Oxu/9PorzM2FZQxeMjVi4RHXP1eoe8eLflJcKpnqgkTJC4HDZtmad/WEBb BQo0ZRya5jLp1HRvTC6u7KCicYg03k1yYMjcYT4nMGQjIihW2Qn2IES8bg0b9oqsoxQ== 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=2re49ded; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=joVtIRfd; 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 51A8A606B2FD for ; Fri, 13 Nov 2026 16:17:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 51A8A606B2FD 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=2re49ded; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=joVtIRfd From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1794586657; 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=YmKdqa9PN50e2UkKt3EfBiqD0YdHB3OU7Jqo14mmKwc=; b=2re49ded+Le750cmPbDqpI3zJEZ/u0Oc7eONWJd3Qs/wtWtK95vs/WF8CGMR/eXxk4XVxy vBmdimlh5qDREKfn+ZDsJcpUO5asyP0EFbiPqTymVB/ifkj8SLDM1tYEqdyn49+lT9njUx Cvyca1ho1k17KvAYgKwuiWa7RJt6so0FJNZxljAqhQtYLRoa0v9k7L5mQEKI21ignQ9SLY RiFFLObI/YzTSciLd3SyhqndDhv/JlsPfP2xpcoJ/NoKebE6MuCZlYk9GLE66fIpEx0raR KAC8L6eMZDsH+XVVxed0tiUc9WoZXOhH4UcRiwp60bypCM/93MOcs0KzEzhqGg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1794586657; 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=YmKdqa9PN50e2UkKt3EfBiqD0YdHB3OU7Jqo14mmKwc=; b=joVtIRfdyNUPxYkkHCdBB1CAhkPjdGqwiluEKQIbr3TaCE7+KYxzMSj6Rw5thx1FJyuZzU Tczgj9z1Yp0y12DQ== To: Tomas Glozar Cc: Daniel Wagner , Steven Rostedt , Sebastian Andrzej Siewior , Clark Williams , linux-trace-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev Subject: Re: [PATCH v2] rtla/timerlat: Lock the memory of the user-space threads In-Reply-To: References: <20261113-rtla-mlock-v2-1-14382f140da0@monom.org> <87o6bswzj9.fsf@jogness.linutronix.de> Date: Fri, 13 Nov 2026 17:23:37 +0106 Message-ID: <87ld6wwvry.fsf@jogness.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 On 2026-11-13, Tomas Glozar wrote: > The only other activities the user thread performs with RT priority on > before entering the timerlat interface read loop are setting the > cgroup and opening the timerlat interface file descriptor. I agree > that ideally, setting the priority should be done just before the > loop. If you say it is ideal to do X, then why not do X? Real-time tasks (especially running at rtprio 95!) need to respect other real-time tasks on the system. Developers new to RT might see this code and copy it. The code even has a comment: "If you want to use as base for your own tool... go ahead." For me there are two issues here: 1. RT latency measurement tooling needs to be a little intrusive to a system as practical. Otherwise it may not be possible for developers to use the tooling on their real environment. 2. Official RT tooling should set the example of how to program for RT Linux correctly. John