From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 488011DBB3A; Thu, 28 May 2026 23:39:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780011550; cv=none; b=fZqLOq59+mmOAu6VWWlSfu+gYfPs2C/azzyA6up5YyEmwi+rqxcOoBjgpYvavtLUvZ6wiibwHyhMlSLYCAb4shLA+0B/v9vWEwAFzcFPjOQA94vs0pMyWE2fZ4PRf8yuS8UTAFuyMQ3TkpgqqB+13Sd+R3yaQ7pvMxZwZyFNWtM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780011550; c=relaxed/simple; bh=iDrTPOX6GGDt+nbh9lhKPL6Ecpsqypq4y6HAaTEnrQQ=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=hmoZWJHYbaYGEuyPZFNe9IFve7P4lLR5gRxKkd1kY4gKlqOOp8eXn2AKFLeljvR+FXLLkH6RKXRgphNmf0raahgXoleIOqd147bBpuZSOI196c4gPe4FTKutJsEDX8IE3g1iL/KZSRzuDbh+JkuGNfkNrkne3Y7OoujhX0tNbqo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RJu+1S94; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="RJu+1S94" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 40B051F000E9; Thu, 28 May 2026 23:39:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780011548; bh=dmBIoxz66k2rHcSMbm0eP8qTyH3vYzffzxZnEsn0ck4=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=RJu+1S94uLW4cQvcEK8SoMGPhXx44RpgTo0OfCuWQXiTAHfsWbNm+PRublWTU+NKE vDoQK+865o528s8QWzzsdGTESQXZJejtxmrghU8AJRmzuEJs2gIIBfha6e4qqOZHu7 9D0FXdHDX5u0wmB9QpOvLPxyMV/99fV8KtzhuLZiJMsGdx7+w2+ntQyDgemmHt8g3P 3rQJgPo5AFRxgXzF/TKi2Jg1WvJ5EXrrugkYpdnfxwpcQLsoZaw/WpeOYPwIlBzaO9 DefqDbXlwI1Qxg8vAmWBzsACIAhMVqqT1YAQUCeWcpKgzbDKOZ8tQWOsjBk+mrzpC0 Ra34TheMbeOaQ== Date: Thu, 28 May 2026 16:39:07 -0700 From: Jakub Kicinski To: Matthieu Baerts Cc: Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Shuah Khan , Florian Westphal , netdev@vger.kernel.org, mptcp@lists.linux.dev, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH net 0/3] selftests: mptcp: reduce bufferbloat and cleanup Message-ID: <20260528163907.619420c3@kernel.org> In-Reply-To: <0e676b57-ca1a-4f2b-8166-a085fe69e0f2@kernel.org> References: <20260527-net-mptcp-sft-bufferbloat-exit-v1-0-9afc4e742090@kernel.org> <20260528144258.58bbc950@kernel.org> <0e676b57-ca1a-4f2b-8166-a085fe69e0f2@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 29 May 2026 09:13:44 +1000 Matthieu Baerts wrote: > Hi Jakub, > > On 29/05/2026 07:42, Jakub Kicinski wrote: > > On Wed, 27 May 2026 22:11:33 +1000 Matthieu Baerts (NGI0) wrote: > >> Bufferbloat is baaaad, even in our selftests: let's kill it (or at least > >> reduce it). By doing that, the tests (seem to) have a more stable > >> transfer, and are then less unstable. That's what patches 1-2 are doing, > >> and they can be backported up to 5.10. > > > > Could you explain a little more what this is actually fixing? > > The simult_flows.sh test simulates very low speed links using netem > qdiscs. With the current configuration, still a large amount of packets > can be queued, which means high TCP RTT samples and then large receive > buffer size. Minimal inaccuracy in the pacing rate can lead to using > only one subflow towards the end of the connection for a considerable > amount of data, while the test expects to use the 2 available paths in > parallel. > > > Does it give a huge increase in test stability? > I would say no: the test was not that flaky, mainly on NIPA in fact, and > around 4% in the last 100 tests [1]. On my side, I had to get my system > busy to reproduce the issues. My hope is that the success rate on NIPA > switches from 96 to ~100%. No failure since its introduction in > "net-next-2026-05-27--15-00". > > I sent them to net, just to increase the stability when validating > stable kernels as well. But all of this is not urgent, and this series > can be applied in net-next if preferred. Do you want me to resend this > series targeting net-next? Thanks for explaining, I will take these via net-next, no problem.