From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id /09VGtEnpmC1UgAAWB0awg (envelope-from ) for ; Thu, 20 May 2021 05:11:45 -0400 Received: by simark.ca (Postfix, from userid 112) id 5EE2C1F11C; Thu, 20 May 2021 05:11:45 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_REPLYTO_END_DIGIT,MAILING_LIST_MULTI, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.2 Received: from lists.lttng.org (lists.lttng.org [167.114.26.123]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 908031E54D for ; Thu, 20 May 2021 05:11:44 -0400 (EDT) Received: from lists-lttng01.efficios.com (localhost [IPv6:::1]) by lists.lttng.org (Postfix) with ESMTP id 4Fm3rw0h90z1rNr; Thu, 20 May 2021 05:11:44 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lists.lttng.org; s=default; t=1621501904; bh=cwI/vr0y6LWvt8DaWh13FMvSZ/I2Ykl85J69AmMtfdE=; h=References:In-Reply-To:Date:To:Cc:Subject:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From:Reply-To:From; b=kWmab8KbC617Ki4DpL+12SxEGyiLwqi2I8paj+KR62MyfCneS9Nv9Zj9vvdMTq+ov onW6FYGw/GvCCNeV7AS0hWOhfD0bGQzXDtYlzmZsvzcLtdjrQFDhI/75FaMVx2QnsW 20uGnwvVMxHX2vxPq+kWsSg5pKjm2Xx/weqvY1NIgKqVgWZk/TNpsG5CZfR1Mzmh6e B1Xach/CyFFi4ZSbLOA55j6Kom3rC+qYnPNvSlsemLquEXjOM6U1RR5Mv+XlVX+AnO KiK8s0vkX9aCw1W/sOqJ4CExysA38rc5/KSnhRARe4y2hLevv/YiP6JJmxpexVTOmT 3hfR4VKGjyLNA== Received: from mail-oi1-x22b.google.com (mail-oi1-x22b.google.com [IPv6:2607:f8b0:4864:20::22b]) by lists.lttng.org (Postfix) with ESMTPS id 4Fm3rv1lKnz1rKk for ; Thu, 20 May 2021 05:11:43 -0400 (EDT) Received: by mail-oi1-x22b.google.com with SMTP id s19so15762935oic.7 for ; Thu, 20 May 2021 02:11:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=mgoZDTfaMtpcH6dMEGkU53W6r0VTnFo6lQABiH+seYk=; b=Ae1Y4ywSl8BpsJBClFlgvKu2exrBQOcWGJ0wGVFaZMetABCgJyajwVcc2baqv23XFf oJe4YlZGp+5PjTCes12LKVYGBijRBqigYNJ5+lg1s8fTmZl/tluUjiNIrYk/Y0U3FQhx 9WqItA3BpV8BuOhnZhuMRUofS/cDPHTq5gMYYskVMEuDGHDTAgRANfLojNZkF6/umn+9 VToFsU0kupbC7GoDY1nVgdmR6RhMN4cpHuhzV9B6AE7w7RRw4ex539I39bIKC6KJN7JB 1nYyyzJkhPHYrkuapIqM+w+qnbtDRd2yprK1bQN6EKgrO6ENc9NpYCtqaVGI81+F4Hn/ PpHg== X-Gm-Message-State: AOAM531hXOPSiH8X4fIXDCNegOTGTrGbbBDTmsTlaI6CDG4Nrv7EzXqu Gasr2/EyGJ0cMl0QG0iTiKlNSEVgseq6EV7Ht/4= X-Google-Smtp-Source: ABdhPJyaTkf96me9bO/rZGA74VssCc2EGxv1ck1j/UdySq+evfhaNE5Kh2yMc5EUfGvFl1yYJnuRjFVjevdKD+nYHqs= X-Received: by 2002:aca:acc7:: with SMTP id v190mr2651228oie.28.1621501902348; Thu, 20 May 2021 02:11:42 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: Date: Thu, 20 May 2021 11:11:31 +0200 Message-ID: To: MONTET Julien Cc: "lttng-dev@lists.lttng.org" Subject: Re: [lttng-dev] LTTng - Xenomai : different results between timestamp-lttng and rt_time_read() X-BeenThere: lttng-dev@lists.lttng.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: LTTng development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Norbert Lange via lttng-dev Reply-To: Norbert Lange Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" Am Do., 20. Mai 2021 um 10:28 Uhr schrieb MONTET Julien : > > Hi Norbert, > > Thank you for your answer ! > > Yes, I am using a Xenomai cobalt - xenomai is 3.1 > cat /proc/xenomai/version => 3.1 > > After the installation, I tested "test tools" in /proc/xenomai/ and it worked nice. Just asked to make sure, thought the scripts usual add some -xeno tag to the kernel version. > What do you mean by "it might deadlock really good" ? clock_gettime will either use a syscall (kills realtime always) or is optimized via VDSO (which very likely is your case). What happens is that the kernel will take a spinlock, then write new values, then releases the spinlock. your program will aswell spin (but just to see if the spinlock is free), read the values and interpolates them. But if your program interrupts the kernel while the kernel holds the lock (all on the same cpu core), then it will spin forever and the kernel will never execute. The ugly truth is, that any library you use could call those functions, you need to very closely look at your realtime path. Some checkers can help: https://github.com/nolange/preload_checkers Norbert. _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev