From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 8087814E2CC for ; Tue, 7 May 2024 10:00:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715076024; cv=none; b=sptrZKp/KVfuf+APqxeT32R2JAJMDpMA1SwdNp/PXhGs/YbmlWRX5Tmg894RlXrYIBwVBCpvmVoDwMeGYkvk5UOLt6uPzSIOGFVHUa/+3ei+0ri3Q/vN+m/U9gr7aAywtxoB8n/7D7lGdEUMRlWFU47Uhcu1D6FNvP5dSC/1oYE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715076024; c=relaxed/simple; bh=ZvcMTBsfgHX+stTQFrOmcHZhoMLFogCJxflmKSkKX7U=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=t32SHoZuetMBkcl9eQzRaWwo2qg9xrNBOeQQdPqgSGWQbArHlPDVR9C4qhdWS57Rho0OLaPJZg7Nl2dbdBzPE8YsjhY9gKpaQjR9lWP3T+bZLlInlMVoYIvk05DgnuXuqGQmZ9Txxr7G87wLPNGzh7hWZY6+cq2S+MNlOyRIXeQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pVtiF/M0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="pVtiF/M0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AFB39C2BBFC; Tue, 7 May 2024 10:00:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1715076024; bh=ZvcMTBsfgHX+stTQFrOmcHZhoMLFogCJxflmKSkKX7U=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=pVtiF/M0KCkXy96LyAGgNitsB5W+tSrYLLD8j/sTBE0m7KEiFN6Xp72rXHO+dXV47 9Q5zcjrWZswCQnh45KN8bny1dNi+4fOY1+bOp28vrGhd1Rzrak7v5Pwz/yGy9rk2MD WGwvRsK1bGbSmh1QG2fpHFUUDHY0Vj2UKrDtoCb3ekLzm/VVYLWJ1ZD0O/IUDRummP X9RTnnbubSL9PWdgFoamlbh50WA6RylEs3A9B7fqEsHRS9eW2BhZ2zMjwhShqwlpp7 URaImLnFvMptRkJraoKSzSySJXpPTpIeyiMcVBd+PiQte/OYVNnmzfAod1+opnDb8q aZM34AcPRKEYw== Message-ID: <70899a25-80ff-4456-bc85-5bba1240bc27@kernel.org> Date: Tue, 7 May 2024 12:00:20 +0200 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH mptcp-net v2] mptcp: fix the default value of scaling_ratio Content-Language: en-GB To: Geliang Tang Cc: martin.lau@kernel.org, Geliang Tang , Paolo Abeni , mptcp@lists.linux.dev References: <0ccc1c26d27d6ee7be22806a97983d37c6ca548c.1715053270.git.tanggeliang@kylinos.cn> <7f9f2b7f-9bb5-4c17-bdef-c96fe2707d27@kernel.org> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Geliang, On 07/05/2024 11:34, Geliang Tang wrote: > Hi Matt, > > On Tue, May 07, 2024 at 10:12:41AM +0200, Matthieu Baerts wrote: >> Hi Geliang, >> >> (+cc Paolo who wrote the commit mentioned by the "Fixes" tag) >> >> On 07/05/2024 05:46, Geliang Tang wrote: >>> From: Geliang Tang >>> >>> BPF tests fail sometimes with "bytes != total_bytes" errors: >>> >>> test_default:PASS:sched_init:default 0 nsec >>> send_data:PASS:pthread_create 0 nsec >>> send_data:FAIL:recv 936000 != 10485760 nr_recv:-1 errno:11 >>> default: 3041 ms >>> server:FAIL:send 7579500 != 10485760 nr_sent:-1 errno:11 >>> send_data:FAIL:pthread_join thread_ret:-11 test_default:PASS: \ >>> has_bytes_sent addr_1 0 nsec >>> test_default:PASS:has_bytes_sent addr_2 0 nsec >>> close_netns:PASS:setns 0 nsec >>> >>> In this case mptcp_recvmsg() gets EAGAIN errors. This issue introduces >>> by commit b8dc6d6ce931 ("mptcp: fix rcv buffer auto-tuning"). The default >>> value of scaling_ratio should be TCP_DEFAULT_SCALING_RATIO, not U8_MAX. >> >> It looks like you are modifying the max value, not the default one. >> >> Also, please always explain the reason: why should it be X, not Y? >> >>> >>> Fixes: b8dc6d6ce931 ("mptcp: fix rcv buffer auto-tuning") >>> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/487 >>> Signed-off-by: Geliang Tang >>> --- >>> v2: >>> - I finally found the root cause of this issue. >>> - cc Martin too. >>> --- >>> net/mptcp/protocol.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c >>> index 579031c60937..d00cd21e8d3f 100644 >>> --- a/net/mptcp/protocol.c >>> +++ b/net/mptcp/protocol.c >>> @@ -1981,9 +1981,9 @@ static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk, >>> */ >>> static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied) >>> { >>> + u8 scaling_ratio = TCP_DEFAULT_SCALING_RATIO; >> >> With this modification, you are limiting msk->scaling_ratio to >> TCP_DEFAULT_SCALING_RATIO. That's probably not what you want. See below: >> >> (...) >> mptcp_for_each_subflow(msk, subflow) >> (...) >> scaling_ratio = min(tp->scaling_ratio, scaling_ratio); >> >> (...) >> msk->scaling_ratio = scaling_ratio; >> >> >> Do you mean that in your case, msk->scaling_ratio was assigned to >> U8_MAX? Or it was assigned to a too high value (>TCP_DEFAULT_SCALING_RATIO)? >> >> Please add such info in the commit message as well. > > Sure. Here's the new subject and commit log: > > ''' > Subject: mptcp: fix the max value of scaling_ratio > > BPF tests fail sometimes (a probability of approximately 1%) with > "bytes != total_bytes" errors: > > test_burst:PASS:open_and_load:burst 0 nsec > test_bpf_sched:PASS:Scheduler name too long 0 nsec > test_bpf_sched:PASS:burst 0 nsec > create_netns:PASS:ip netns add mptcp_ns 0 nsec > create_netns:PASS:ip -net mptcp_ns link set dev lo up 0 nsec > sched_init:PASS:create_netns 0 nsec > endpoint_init:PASS:ip -net mptcp_ns link add veth1 type veth peer name > endpoint_init:PASS:ip -net mptcp_ns addr add 10.0.1.1/24 dev veth1 0 nsec > endpoint_init:PASS:ip -net mptcp_ns link set dev veth1 up 0 nsec > endpoint_init:PASS:ip -net mptcp_ns addr add 10.0.1.2/24 dev veth2 0 nsec > endpoint_init:PASS:ip -net mptcp_ns link set dev veth2 up 0 nsec > endpoint_init:PASS:ip -net mptcp_ns mptcp endpoint add 10.0.1.2 subflow > sched_init:PASS:endpoint_init 0 nsec > test_bpf_sched:PASS:burst 0 nsec > send_data_and_verify:PASS:burst 0 nsec > send_data_and_verify:PASS:burst 0 nsec > (network_helpers.c:613: errno: Resource temporarily unavailable) \ > send 5608500 expected 10485760 > (network_helpers.c:661: errno: None) recv 2755984 expected 10485760 > (network_helpers.c:669: errno: None) Failed in thread_ret -11 > send_data_and_verify:FAIL:send_recv_data unexpected error: -4 (errno 0) > #162/9 mptcp/burst:FAIL > #162 mptcp:FAIL > > In this case, mptcp_recvmsg() gets EAGAIN errors. This issue introduces > by commit b8dc6d6ce931 ("mptcp: fix rcv buffer auto-tuning"). The max > value of scaling_ratio should be TCP_DEFAULT_SCALING_RATIO (128), not > U8_MAX (255). Otherwise, scaling_ratio is assigned to a too high value. > ''' Sorry, I'm still not sure whether I understand the issue: - Why limiting to the default value? - Here, we want the higher scaling_ratio from all the available subflows: is this value too high? What "too high value" you got that was causing the issue you mentioned? - What is a "too high value" for you and why? - Or is it because scaling_ratio was assigned to U8_MAX and not changed to the max value of the subflows by accident because there was a bypass somehow? Cheers, Matt -- Sponsored by the NGI0 Core fund.