From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33776C433EF for ; Sun, 12 Jun 2022 23:30:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237785AbiFLXan (ORCPT ); Sun, 12 Jun 2022 19:30:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232812AbiFLXak (ORCPT ); Sun, 12 Jun 2022 19:30:40 -0400 Received: from mail-yb1-xb33.google.com (mail-yb1-xb33.google.com [IPv6:2607:f8b0:4864:20::b33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6829C54187 for ; Sun, 12 Jun 2022 16:30:39 -0700 (PDT) Received: by mail-yb1-xb33.google.com with SMTP id t32so7273738ybt.12 for ; Sun, 12 Jun 2022 16:30:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=fSaAxK/sjwEAdJ0xVDT8/xNpyJ/5T+h2sZVRU4bYEY0=; b=Wb11KzRC251PpEFgIE6escV9Dfn+eILU3vMR4xh2V6EHTqVDngKlX7COztDCxS1ggA VReXCQT6ybasBP5v/TrwZk3CoOssl5lWMUPAzSwkG4wS+tTcl87fWBQtfeaNiBoUHWp+ zkJh/5j7sPzCi4d5nN9FyNmUSXJyoWJdFuY8AZwRhthG5VB1aW40d12FOhRpQ/vA31GF DC6dErIImTLTCgy4atRg3jz94b7jgFzQuC6D8hLNPlBsevC7ceMUB5SLKNXZnhza2ODq M04zsGh8o/Q3ZyeDeBIZmE53fDqkqGYl94aCmomHfD33cxrWkQa7ubRxAJ3+Q46wxwfA U3vw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=fSaAxK/sjwEAdJ0xVDT8/xNpyJ/5T+h2sZVRU4bYEY0=; b=5+jeZdujbsUdO7I5XKa630M7zMyk3X6Us6CBqBTQFfjU4see942fQMHHbLSpOje/N3 e2QVTvcClckvESdMnxA/7YyLeuDmMHuFB/Krs6WqGjVsU0ktB5tKh5iUD2rruDZze/oH OAuMHBOM03m/EN3nbe55zy5iFNVXQF1fY/zmu25G366MpIdVyGuaqxlAHRrAIs9TaqEM GVg7nlsRJZzM7oRnM60lT7IICw6M5w1eE6a8rHMWXvNaxYq559EqVLKcF2PznMirEIyy c4o64sW4fsIKgnt6u4SgQrAYsxDCmPmjLsxbdSZvFXBpJGQIycAg3MH4R6nWdH3hYyjQ yHqg== X-Gm-Message-State: AOAM533bR5jM8O05yQevz/3cksIYC5nVlOA4TnzdwzYlPaEVXXD5cD8j DqVugWT4/hCOvmhzRDcf/1r2X337ntn7IOgkEn20OEGp X-Google-Smtp-Source: ABdhPJwiILPZWUpes4rrwhkafz3EszitYKgpKNG64GltNHkUCTDoiV+uydCymPnlzHVdAWVHOQlqqR5ir/Mu3QHuNNI= X-Received: by 2002:a25:4544:0:b0:660:63fc:9d41 with SMTP id s65-20020a254544000000b0066063fc9d41mr51396747yba.600.1655076638591; Sun, 12 Jun 2022 16:30:38 -0700 (PDT) MIME-Version: 1.0 References: <87y1y48spg.fsf@jogness.linutronix.de> <87zgihlbst.fsf@jogness.linutronix.de> In-Reply-To: <87zgihlbst.fsf@jogness.linutronix.de> From: Peter Geis Date: Sun, 12 Jun 2022 19:30:27 -0400 Message-ID: Subject: Re: [BUG] Threaded printk breaks early debugging To: John Ogness Cc: Petr Mladek , Sergey Senozhatsky , Linux Kernel Mailing List , "open list:ARM/Rockchip SoC..." Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jun 12, 2022 at 7:08 PM John Ogness wrote: > > On 2022-06-10, Peter Geis wrote: > > This might be a side effect of the fact that this is on a low powered > > arm64 board. I noticed with threading enabled during large bursts the > > console drops an excessive amount of messages. It's especially > > apparent during the handover from earlycon to the normal console. > > I guess you have a very small kernel buffer and are generating unusually > high amounts of messages? Is there a reason you cannot use a larger > buffer? The buffer isn't an issue here, everything is available in dmesg when userspace becomes available. Instead some messages bound for the serial console are never output. > > Or maybe you are generating a constant amount of messages that a serial > port could never keep up with unless it was interfering with the system > in such a way as to slow everything down? This is exactly what printk > should _not_ be used for. We run a serial console at 1.5m baud which is significantly higher than most SoCs which default to 115200. I have noticed some timing differences since the introduction of the threaded console. A significant amount of information is dumped very early in the boot process (between 0 and 4 seconds into boot), as most drivers are probing during this time. It also happens to be when the earlycon console hands over to the normal console. There is no abnormal debugging enabled, the output is a standard (non-quiet) boot log. The question is why is direct mode not triggering during a panic? > > John Ogness From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 92ACFC43334 for ; Sun, 12 Jun 2022 23:30:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:Subject:Message-ID:Date:From: In-Reply-To:References:MIME-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ZrPRGfMu6TLCrsrStXLMhDiO6IijZCUHBWmrzAbkVPI=; b=dyDqekBXoDqZOY WWtlP3oE4pDOaDEPc8Faayu/8tTXqwy4Tcbj91VryUNSm3ryU/NWk/7EwvqO+p8L867jJkY3qIFhl tKcHvTMc+ls6N/sJoEE+dNq46DEz3uyydpxqaKHQ2DnooKEyiu3LFRax/ZGdpQzcmap+O7HB2oqYv gu6A0WnSBmIvLE1XwFf1kQhlCDAHD7ME1ijrJZUQ7Ijodu/R2Rk1rdFF4KZ9OtO2d6w9UyaF0jakE FXn6Zb0II+5GpCuDL9rncNpGITdvt6991mj6d+s/VwIZgsf7hQHRjKBA/KkYyrdcKu69+j7DXuxhi jKNZ3xyr4sUYOTo14qtg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o0X2Y-000XUt-Sr; Sun, 12 Jun 2022 23:30:42 +0000 Received: from mail-yb1-xb2b.google.com ([2607:f8b0:4864:20::b2b]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o0X2W-000XUX-HD for linux-rockchip@lists.infradead.org; Sun, 12 Jun 2022 23:30:41 +0000 Received: by mail-yb1-xb2b.google.com with SMTP id x38so7309261ybd.9 for ; Sun, 12 Jun 2022 16:30:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=fSaAxK/sjwEAdJ0xVDT8/xNpyJ/5T+h2sZVRU4bYEY0=; b=Wb11KzRC251PpEFgIE6escV9Dfn+eILU3vMR4xh2V6EHTqVDngKlX7COztDCxS1ggA VReXCQT6ybasBP5v/TrwZk3CoOssl5lWMUPAzSwkG4wS+tTcl87fWBQtfeaNiBoUHWp+ zkJh/5j7sPzCi4d5nN9FyNmUSXJyoWJdFuY8AZwRhthG5VB1aW40d12FOhRpQ/vA31GF DC6dErIImTLTCgy4atRg3jz94b7jgFzQuC6D8hLNPlBsevC7ceMUB5SLKNXZnhza2ODq M04zsGh8o/Q3ZyeDeBIZmE53fDqkqGYl94aCmomHfD33cxrWkQa7ubRxAJ3+Q46wxwfA U3vw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=fSaAxK/sjwEAdJ0xVDT8/xNpyJ/5T+h2sZVRU4bYEY0=; b=SrSWjEQHLoBXDnoS9nq+xc1KGKgEIf6pid8VTpNLlKCvZEE77bC/Q8XYRRj9tnfFXo esxYwirzQWYlu7fKpxRxrnIuym+F/8k/IAiAeIKnMJjEqZY42DCw693GtxpGBft1QeE3 LyyQ/pGLjMhe+ZhskmyU52wLbb/Del6uzzjwDNqytsTKCU+CT2m2YFpVwk82HtZ2nzyd 2X0XW3wJCn31R7gruPqsU6/cttiXFElqx6H8nAvTluCyXDWnWS7ecsPFKpcqevzCSsju lObslko0GTAxOdHbLgdnpZnusSNXHm4F8Z8RE8MF6qdQvJdGlW5S1tEwBxAWiaamgd4U oX2g== X-Gm-Message-State: AOAM530hlF42geHooRhH8FSr7sSgL741eYtJPWHPM3pH57YEjLEufF6e BZziK3QRcwkOD8kCbQOuMg6rzHkDqI1stlnszQM= X-Google-Smtp-Source: ABdhPJwiILPZWUpes4rrwhkafz3EszitYKgpKNG64GltNHkUCTDoiV+uydCymPnlzHVdAWVHOQlqqR5ir/Mu3QHuNNI= X-Received: by 2002:a25:4544:0:b0:660:63fc:9d41 with SMTP id s65-20020a254544000000b0066063fc9d41mr51396747yba.600.1655076638591; Sun, 12 Jun 2022 16:30:38 -0700 (PDT) MIME-Version: 1.0 References: <87y1y48spg.fsf@jogness.linutronix.de> <87zgihlbst.fsf@jogness.linutronix.de> In-Reply-To: <87zgihlbst.fsf@jogness.linutronix.de> From: Peter Geis Date: Sun, 12 Jun 2022 19:30:27 -0400 Message-ID: Subject: Re: [BUG] Threaded printk breaks early debugging To: John Ogness Cc: Petr Mladek , Sergey Senozhatsky , Linux Kernel Mailing List , "open list:ARM/Rockchip SoC..." X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220612_163040_629581_F6151A00 X-CRM114-Status: GOOD ( 16.61 ) X-BeenThere: linux-rockchip@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Upstream kernel work for Rockchip platforms List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+linux-rockchip=archiver.kernel.org@lists.infradead.org On Sun, Jun 12, 2022 at 7:08 PM John Ogness wrote: > > On 2022-06-10, Peter Geis wrote: > > This might be a side effect of the fact that this is on a low powered > > arm64 board. I noticed with threading enabled during large bursts the > > console drops an excessive amount of messages. It's especially > > apparent during the handover from earlycon to the normal console. > > I guess you have a very small kernel buffer and are generating unusually > high amounts of messages? Is there a reason you cannot use a larger > buffer? The buffer isn't an issue here, everything is available in dmesg when userspace becomes available. Instead some messages bound for the serial console are never output. > > Or maybe you are generating a constant amount of messages that a serial > port could never keep up with unless it was interfering with the system > in such a way as to slow everything down? This is exactly what printk > should _not_ be used for. We run a serial console at 1.5m baud which is significantly higher than most SoCs which default to 115200. I have noticed some timing differences since the introduction of the threaded console. A significant amount of information is dumped very early in the boot process (between 0 and 4 seconds into boot), as most drivers are probing during this time. It also happens to be when the earlycon console hands over to the normal console. There is no abnormal debugging enabled, the output is a standard (non-quiet) boot log. The question is why is direct mode not triggering during a panic? > > John Ogness _______________________________________________ Linux-rockchip mailing list Linux-rockchip@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-rockchip