From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf1-x131.google.com (mail-lf1-x131.google.com [IPv6:2a00:1450:4864:20::131]) (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 AFAB03B2A4 for ; Mon, 22 Jun 2020 09:11:15 -0400 (EDT) Received: by mail-lf1-x131.google.com with SMTP id u25so9604893lfm.1 for ; Mon, 22 Jun 2020 06:11:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to:cc; bh=/u5yAPxKUNQ3BOuZnWEksh38cHAg48bj+tiU84KA8MY=; b=ZyTpXy+hUkCtXDLO5xQWo3lPl26NlQaWrg731+qItG7esr8ON/M1rMR/VemO6VEawF PaWo17OWJSOnq94XVXfkbt7YLh7/nwmiS+A2O8/XFeRV1Jj2Np3eIl5cLDJnfBiDCTCd pjdgUoaEf++OKcGQlK6SzmyYhsPg+QJhwreaN5YY1Kfe5ql8K5ODGhF42/Y1GZ+L2l8m VBfy/budoSwe9e2RkG8rrC6mGrL4mR6o8VTc13/4dKpjTbikPpLPACtz6q6jXMXBcIB/ 7U+AcAKVC8p53VE8VLbrfCAxcxbrVlGlYGJrGePC/5Pot6IxMPohoG68SZqNOeFv/Zxl LRRg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to:cc; bh=/u5yAPxKUNQ3BOuZnWEksh38cHAg48bj+tiU84KA8MY=; b=ZuB2DfsJ+mpU0UDpWdYjZVJsRHb2GPDpSv3E1xQBfSQtIwfsP9utpsOzqSLRrPOKvI cY6t0bbgatE9a60qroz07zxUTTFujFHl4N/mWJb/AhIUVX56scrdA+wCmXb6qch2iU+Z VK1Ay+ieODeTzGX17+AB/fc0hrxssXiLZje4G1mXgcOcrLjYPuenHfP8NUUCX1mVScpD JdNHl73ynPQhBHjWSfEy+rnGQcjlQK/fYd4LeptztpOrTv+d49VMTjgbdcKGuCMhi+1i UoUfFR9pz1aHwTbg9Bk51d3goCXUL820msOP01QDQKW/PdCXznIitgeD+CuNIXINIl30 hlxA== X-Gm-Message-State: AOAM532FaymuTXJjMvZCL5VMb0xQMym6Ui/vDzQS+khU5ynCTbm7T9WD lK2sMfRrlG4F4bJrGHuqOWb4mQ9UJCokvCgdXF0l1uJG X-Google-Smtp-Source: ABdhPJz2qWa9yTyhLLn97dc1XvLLgg4BfvEKJu20I7EZ1UBAWmGcGDm5Zkkd57nZGfnuA3eoR0ispyuchrZANS5RbeY= X-Received: by 2002:a19:23cc:: with SMTP id j195mr9810214lfj.210.1592831474127; Mon, 22 Jun 2020 06:11:14 -0700 (PDT) MIME-Version: 1.0 From: Jose Blanquicet Date: Mon, 22 Jun 2020 15:10:37 +0200 Message-ID: To: cake@lists.bufferbloat.net Cc: marco maniezzo Content-Type: text/plain; charset="UTF-8" Subject: [Cake] [CAKE] Rate is much lower than expected - CPU load is higher than expected X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 22 Jun 2020 13:11:16 -0000 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