From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sonic308-44.consmr.mail.ir2.yahoo.com (sonic308-44.consmr.mail.ir2.yahoo.com [77.238.178.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 0F0D13B2A4 for ; Mon, 22 Jun 2020 10:27:12 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.fr; s=s2048; t=1592836032; bh=b37NSUdvkerGYgCO8JRnNf1IP7s6Waa5/RrShXPbLyY=; h=Subject:To:References:From:Date:In-Reply-To:From:Subject; b=DpM+pwD+SfKPxlnpnkKa2BYNQYh0kdh1+SZjzKLRAN6391paGLe2xWirmynmvvC/f0bki+gKFtz0FJCYM1zhQdmrGxM10rN/vBKm9j8TmJcYbYgnmvS2F3z5BFSDYSIE65dl9211w774mOHxMq6xjuJ/AB2JFoPU0DulVhEa2SfrLWU6DIi78KvsmmLLGnhRvCz71j4BpGJAi2q3DkG8IbLBA7mCqLcpitBQXrZj7FQrs5aPmVDfcF6wiUG2E8GjjLb30yzqOKFVcAZorKKI6c1OnHvfROffTI+N0pFjdwGX7s6OlPKf5OJ4tK9t3kp7HJwX041XGdzcmf8HqqSUCA== X-YMail-OSG: N_6BpMEVRDvd.miR6A7lED5GPdAEx7ojsA-- Received: from sonic.gate.mail.ne1.yahoo.com by sonic308.consmr.mail.ir2.yahoo.com with HTTP; Mon, 22 Jun 2020 14:27:12 +0000 Received: by smtp411.mail.sg3.yahoo.com (VZM Hermes SMTP Server) with ESMTPA ID 65a622fe53d916d3d79f7e1e79711216; Mon, 22 Jun 2020 14:25:10 +0000 (UTC) Subject: Re: [Cake] [CAKE] Rate is much lower than expected - CPU load is higher than expected To: cake@lists.bufferbloat.net References: From: Y Message-ID: Date: Mon, 22 Jun 2020 23:25:05 +0900 User-Agent: Mozilla/5.0 (X11; Linux armv7l; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Mailer: WebService/1.1.16138 hermes_yahoo Apache-HttpAsyncClient/4.1.4 (Java/11.0.7) X-List-Received-Date: Mon, 22 Jun 2020 14:27:13 -0000 You should paste this result. tc -s qdisc show dev eth0 Yutaka On 22/06/2020 22:10, Jose Blanquicet wrote: > Hi everyone, > > We have an embedded system with limited CPU resources that acts as a > gateway to provide Internet access from LTE to a private USB-NCM > network (And also to a Wi-Fi private network but we will work on it > later). Our problem is that the bandwidth on LTE and USB link is > higher than what the system is able to handle thus it reaches 100% of > CPU load when we perform a simple speed test from a device on the > private network. > > Therefore, we want to limit the bandwidth to avoid system getting > saturated in such use-case. To do so, we thought to use the CAKE on > the USB interface. For instance, we tried: > > tc qdisc replace root dev eth0 cake bandwidth 20mbit ethernet > internet flowblind nonat besteffort nowash > > It worked correctly and the maximum rate was limited but there are two > things that are worrying us: > > 1) The maximum rate reached after applying CAKE was in between 12Mbps > and 15Mbps which is quite lower than the 20Mbps we are configuring, we > were expecting around 18-19. Why? Is there something in the parameters > we are doing wrong? Please take into account that our goal is to limit > the rate but adding as little CPU load as possible. > > 2) The CPU load added by CAKE was not negligible for our system. In > fact, we compared the CPU load when limitation was done by CAKE and by > the device on the private network, e.g. curl tool with parameter > "--limit-rate". As a result, we found that the CPU load when using > CAKE was 30%. Is there any way to make it lighter with a different > configuration? > > Thanks in advance for the support. Any suggestion is welcome. > > Jose Blanquicet > _______________________________________________ > Cake mailing list > Cake@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cake >