From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mx1.redhat.com", Issuer "DigiCert SHA2 Extended Validation Server CA" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 30B5D21F32F for ; Tue, 21 Oct 2014 07:51:11 -0700 (PDT) Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s9LEp1tp018734 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 21 Oct 2014 10:51:01 -0400 Received: from [10.34.26.230] (dhcp-26-230.brq.redhat.com [10.34.26.230]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id s9LEoxv2017416; Tue, 21 Oct 2014 10:51:00 -0400 Message-ID: <544672D3.8020709@redhat.com> Date: Tue, 21 Oct 2014 16:50:59 +0200 From: Michal Schmidt User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.1 MIME-Version: 1.0 To: Valdis.Kletnieks@vt.edu References: <121767.1413574248@turing-police.cc.vt.edu> <9382.1413826910@turing-police.cc.vt.edu> In-Reply-To: <9382.1413826910@turing-police.cc.vt.edu> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 Cc: "cerowrt-devel@lists.bufferbloat.net" Subject: Re: [Cerowrt-devel] SQM in mainline openwrt, fq_codel considered for fedora default X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Oct 2014 14:51:40 -0000 On 10/20/2014 07:41 PM, Valdis.Kletnieks@vt.edu wrote: > On Mon, 20 Oct 2014 10:03:55 -0700, Dave Taht said: >> See: >> >> http://cgit.freedesktop.org/systemd/systemd/commit/?id=e6c253e363dee77ef7e5c5f44c4ca55cded3fd47 > > Those guys must be stopped. Yet another time they tweak a kernel parameter > without bothering to check the return code. Well, the return code is checked, but in case of -ENOENT the error message is intentionally downgraded to debug level: http://cgit.freedesktop.org/systemd/systemd/tree/src/sysctl/sysctl.c?id=14f27b4e3b009d10bb9a3b43b74585c73a7c7626#n105 I guess the intention is to not bother warning about sysctls that get removed from new kernels. Unfortunately, writing an invalid default_qdisc returns -ENOENT, causing write_string_file() to return the same, confusing apply_sysctl() into thinking the sysctl does not exist at all. We can certainly improve that. > (Yes, I'm still pissed at them for suddenly deciding to require cgroup > support in the kernel, and not even adding a check at startup and a > printf "Sorry, no cgroup support found". It just kept going, trying > to use cgroups support taht wasn't there, and hilarity and hijinks > ensued... Suddenly? CONFIG_CGROUPS was systemd's requirement from its very beginning. It used to print: Failed to mount /sys/fs/cgroup: No such file or directory. and stop booting at this point. This was changed in 2011 in response to Ingo Molnar's request to be able to test !CGROUPS kernels. So systemd try to boot after printing this warning: CONFIG_CGROUPS was not set when your kernel was compiled. Systems without control groups are not supported. We will now sleep for 10s, and then continue boot-up. Expect breakage and please do not file bugs. Instead fix your kernel and enable CONFIG_CGROUPS. Since running on !CGROUPS kernels was not in anybody's test plans, the ability to boot without cgroups later bitrotted. When it was noticed in May 2014, the code was reverted to again consider the failure to mount cgroups as fatal and print the original error message. I don't know what hilarity you observed, but at no point should the failure to mount cgroups have been silent. Regards, Michal