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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0CD9EC43331 for ; Fri, 6 Sep 2019 02:50:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 14BA2207E0 for ; Fri, 6 Sep 2019 02:50:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="o68Bclrx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392041AbfIFCu2 (ORCPT ); Thu, 5 Sep 2019 22:50:28 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:42095 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391203AbfIFCu1 (ORCPT ); Thu, 5 Sep 2019 22:50:27 -0400 Received: by mail-pf1-f193.google.com with SMTP id w22so3288162pfi.9; Thu, 05 Sep 2019 19:50:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=VgjVGE6lmfxhygBnBRcl9Vrz9pus5n253xhtFVc0NKA=; b=o68BclrxtpBqJvfD6tSNsOFflIRQ/l2ADb5wWCZzJFChRYr6SktchPaV1FNPE8jsaq nS1tdR7qtKYNTi4a95CJW5tOvBGQ7Az5OmBlRAbJMVp07NepKODC2NDEf+Ke3OkPiZtC KzMfZec26XSCrNPUxtNQrTVXVUTZeiWr6w8RNxY/5Bj06hPLduV6m0ZKbpAjoQTXOInB KRt5CgZJvv1kLuUgv6j223ouAe8bcR1pi8/KUnaLSenkuN0huOyjSav85wLh2Pr2572F peq8dLUF4fxx1mxfUxzUF5Y0N/bMi21gt2QnIFhHhYV253NTJ4WRSOFj0dFwKnnrXfo/ zuHA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=VgjVGE6lmfxhygBnBRcl9Vrz9pus5n253xhtFVc0NKA=; b=tqwVi4TlVAT7g0CRv017P6U+RjvwanZ6/Jd0U6qTPKqY6HsePXh0fezkpt8yQg+2Vw V8oH0sM1OVt5fO0jHvbhHdOzodbDmO7xNkOPwiMszpZzVPA6Hx4Gfeq0TYRNxNWs5yRN 0j7BHTYVcs9wtdmpal3qrKDHpkcKDMOxC6ZiW83LTlFWB75iPfBhNu4cEWS3bWu0s5OD XjvOWMeiYK6/xY/83z/UtVAHp8SONAlxUGS1wSLgr0H7mjl58E1+DnGeZIt1ThlZAUf6 baWJ+u2GDyFpN8j39s3p1qrjPjHj4ahuI+EvnTbt8OUuHDmQMlK7Wvsx+ENTZ4Vv8g36 WpCw== X-Gm-Message-State: APjAAAXaXwLnK/Vd+SL98nnjZdSBXdFNWWqA2CxRkNgzIE/5bwe6Lh4x 6rQyUcz5Oo4enP1bZBr6T74= X-Google-Smtp-Source: APXvYqyh56I11YbI0Ls757lx16cnPwBBUbXbnLk+XuviLZKkM437vuzYWKlS3jQNm4KSJM77TTynwA== X-Received: by 2002:a17:90a:2e15:: with SMTP id q21mr7246465pjd.97.1567738226815; Thu, 05 Sep 2019 19:50:26 -0700 (PDT) Received: from localhost ([175.223.27.235]) by smtp.gmail.com with ESMTPSA id p68sm8147568pfp.9.2019.09.05.19.50.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Sep 2019 19:50:25 -0700 (PDT) Date: Fri, 6 Sep 2019 11:50:22 +0900 From: Sergey Senozhatsky To: Steven Rostedt Cc: Qian Cai , Sergey Senozhatsky , Petr Mladek , Sergey Senozhatsky , Michal Hocko , Eric Dumazet , davem@davemloft.net, netdev@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net/skbuff: silence warnings under memory pressure Message-ID: <20190906025022.GA1253@jagdpanzerIV> References: <20190904064144.GA5487@jagdpanzerIV> <20190904065455.GE3838@dhcp22.suse.cz> <20190904071911.GB11968@jagdpanzerIV> <20190904074312.GA25744@jagdpanzerIV> <1567599263.5576.72.camel@lca.pw> <20190904144850.GA8296@tigerII.localdomain> <1567629737.5576.87.camel@lca.pw> <20190905113208.GA521@jagdpanzerIV> <1567699393.5576.96.camel@lca.pw> <20190905131413.0aa4e4f1@oasis.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190905131413.0aa4e4f1@oasis.local.home> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (09/05/19 13:14), Steven Rostedt wrote: > > Hmm, from the article, > > > > https://en.wikipedia.org/wiki/Universal_asynchronous_receiver-transmitter > > > > "Since transmission of a single or multiple characters may take a long time > > relative to CPU speeds, a UART maintains a flag showing busy status so that the > > host system knows if there is at least one character in the transmit buffer or > > shift register; "ready for next character(s)" may also be signaled with an > > interrupt." > > I'm pretty sure all serial consoles do a busy loop on the UART and not > use interrupts to notify when it's available. Yes. Besides, we call console drivers with local IRQs disabled. -ss