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Subject: Re: [BUG] Threaded printk breaks early debugging Message-ID: References: <87y1y48spg.fsf@jogness.linutronix.de> <8735g9mqo0.fsf@jogness.linutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <8735g9mqo0.fsf@jogness.linutronix.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220612_204912_308536_B8D64B53 X-CRM114-Status: GOOD ( 11.39 ) 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 (22/06/13 01:08), John Ogness wrote: > On 2022-06-12, Sergey Senozhatsky wrote: > > Should a situation when we have only one online CPU be enough of a > > reason to do direct printing? Otherwise we might not have CPUs to > > wakeup khtread on, e.g. when CPU that printk is in atomic section for > > too long. > > IMHO, no. Especially in that situation, we do not want printk causing > that atomic section to become even longer. If the machine has entered > normal operation, we want printk out of the way. At the same time printk throttles itself in such cases: new messages are not added at much higher pace that they are printed at. So we lower the chances of missing messages. _______________________________________________ Linux-rockchip mailing list Linux-rockchip@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-rockchip 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 96279C433EF for ; Mon, 13 Jun 2022 03:49:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233333AbiFMDtO (ORCPT ); Sun, 12 Jun 2022 23:49:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42738 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232683AbiFMDtL (ORCPT ); Sun, 12 Jun 2022 23:49:11 -0400 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4074318377 for ; Sun, 12 Jun 2022 20:49:09 -0700 (PDT) Received: by mail-pj1-x102a.google.com with SMTP id g10-20020a17090a708a00b001ea8aadd42bso4804874pjk.0 for ; Sun, 12 Jun 2022 20:49:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=36dPqle/rlmpKapipF+KE1d4JPgoWr3C6RG6AlhQkWA=; b=Ugkkbu10YeDB3fFkCXZ732hz1icH485fPCKzAPb6Hfdy9IcTXnhDHiCTgWBulae2sI HCTEP9hdisGZk9fh5/56WCLuBfYD0VKVqsRLRXvFXo+v05O1bUIShZDIJR2hd1dZmmIM FXNZ5iOZ7IlBKe9WI5ZamyPsEBFlkXuIRi6U0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=36dPqle/rlmpKapipF+KE1d4JPgoWr3C6RG6AlhQkWA=; b=Qji6PgU76OJN/XNBTPQhnmpkA2yJhoVXqb1U6tpDgp1rznze+CcQq15vdhVw4cbQJy buJDFsnjWZQOgog8GA3ACead6ucBs58zd8XzEBYY71bDdexx1nZrB/vgvT0KN+Ip8yjn vgxQ4bcudAnkDH8sUGp7KSoFN8fD4WAJjxGzpwQfHGsTK8rWdFFNiw37n+hjQ5BwXJIr zd/m38rMbfZKQNFI6fyIpBFu1xrSFuOvf5HCCUj5ANcksLL2/t8ihISr9SlkehJXAtVe FgNNjiLjebxXlsJRCd1PIxOUzR8EgfFsF9LlKywum23yQZytyeRuZLpRIqByM3hFYcSM +v/w== X-Gm-Message-State: AOAM5329q+WVohtuuIgL+x3vOanSkdiG+nYIoi9obC/SAd/9k3aMyCMH +UlE6kFJEVHx0PgbjkZhhIDQ1w== X-Google-Smtp-Source: ABdhPJzp4MllA13fAg38/cBxUsQG0hCqm8mssIZuQ/i/A4EmGw1NniOS8zrFvEDb+JlT9qh2I9h7Vg== X-Received: by 2002:a17:90b:1c8f:b0:1b8:c6dc:ca61 with SMTP id oo15-20020a17090b1c8f00b001b8c6dcca61mr13258788pjb.13.1655092148795; Sun, 12 Jun 2022 20:49:08 -0700 (PDT) Received: from google.com ([240f:75:7537:3187:de22:3777:8b31:5148]) by smtp.gmail.com with ESMTPSA id m26-20020a63941a000000b003fc5b1db26fsm4150680pge.52.2022.06.12.20.49.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 12 Jun 2022 20:49:08 -0700 (PDT) Date: Mon, 13 Jun 2022 12:49:03 +0900 From: Sergey Senozhatsky To: John Ogness Cc: Sergey Senozhatsky , Petr Mladek , Peter Geis , Linux Kernel Mailing List , "open list:ARM/Rockchip SoC..." Subject: Re: [BUG] Threaded printk breaks early debugging Message-ID: References: <87y1y48spg.fsf@jogness.linutronix.de> <8735g9mqo0.fsf@jogness.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8735g9mqo0.fsf@jogness.linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (22/06/13 01:08), John Ogness wrote: > On 2022-06-12, Sergey Senozhatsky wrote: > > Should a situation when we have only one online CPU be enough of a > > reason to do direct printing? Otherwise we might not have CPUs to > > wakeup khtread on, e.g. when CPU that printk is in atomic section for > > too long. > > IMHO, no. Especially in that situation, we do not want printk causing > that atomic section to become even longer. If the machine has entered > normal operation, we want printk out of the way. At the same time printk throttles itself in such cases: new messages are not added at much higher pace that they are printed at. So we lower the chances of missing messages.