From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jcAL61BJ" Received: from mail-pf1-x42c.google.com (mail-pf1-x42c.google.com [IPv6:2607:f8b0:4864:20::42c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40538116 for ; Mon, 4 Dec 2023 10:38:30 -0800 (PST) Received: by mail-pf1-x42c.google.com with SMTP id d2e1a72fcca58-6ce557298f6so830467b3a.3 for ; Mon, 04 Dec 2023 10:38:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1701715109; x=1702319909; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=D9do+LSRoIck+Qn+ildOHg4179ETtCBAEZT+5wXNKAA=; b=jcAL61BJS90/mKdG+FUiCpo8xLxbVIUcNQK/grySgcY3dD8lCy/Y+30U7w4k4O1hca sAx/2KImLsujz7i4PaCDk1T9nmvMaJk7yDDVBMVdvVBBtvmv07R+zeL8txxJTxFcPQnE V633DFHFO4KINyMNsiH4T+YsZuLHGxofvjfVWU8hhdgcLGPZhhMogIPaAetZ86lLAiKw vM7I4PkNg/3KZa0iIRj2A/Wcl+prSvA+9MH7J0qHbOmD+iWErkW72YzWOJ+8SVCVLVtJ Z7GfzpNv7TcCh2+Huzxkcxa0JuGRSKz60f+newaLg/RfOZJZNKR2ssyz7m3gl3fp6+Wi JhKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701715109; x=1702319909; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=D9do+LSRoIck+Qn+ildOHg4179ETtCBAEZT+5wXNKAA=; b=XpnPpA+YNg9D7ydz30QNAlzbCcMpuKx2bSXG1OFcaaeIekFb2gJITpGSPvJtQ8Cs4S /eWzKpwu/9u0s1zSTycR+VLuCto5pWr0uvWoFFXi4U0FQ8iINuViXO0kTDyxg4QBR7fR nMb2bCb/araqpk7fsscD7A8TXhQ3a+3os6DQxjby2DoeP4cqXB2u+Gt7vRN9NHo2Zuw9 pMhTxl/pXBGHCMqGBfbuGSxx9RZ5/pWtwv9M9YgjOsXwJoeMPTg+mw72OVEWQbhtSqXf 4h/r9djq7LAQhJN9fAzsRcztHOLKZrt5OtFq3Ps0lOjmfVBr/a3YRgWqVPEotm69ReHM UtPQ== X-Gm-Message-State: AOJu0YxAhqrJ5SSidKemD4MC8qaK79qJzTW22IusBVS7x4l5aiKO14ou mGeMVxoZe2qI1VIHKRo4UFKChhnrnHnV2MdX X-Google-Smtp-Source: AGHT+IFcyyjWwJjrXmbvqg+BpD37A0zQsRAVAvOSWNkjhV29ujNkG+S6rV4qiPsw/LfHxW1VmZbEAw== X-Received: by 2002:a05:6a20:7f83:b0:18f:97c:b9f6 with SMTP id d3-20020a056a207f8300b0018f097cb9f6mr3461232pzj.80.1701715109293; Mon, 04 Dec 2023 10:38:29 -0800 (PST) Received: from hdebian.corp.toradex.com ([201.82.41.210]) by smtp.gmail.com with ESMTPSA id it4-20020a056a00458400b006cbb58301basm8238299pfb.19.2023.12.04.10.38.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Dec 2023 10:38:28 -0800 (PST) From: Hiago De Franco To: linux-usb@vger.kernel.org Cc: Oliver Neukum , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Hiago De Franco Subject: Question regarding CDC NCM and VNC performance issue Date: Mon, 4 Dec 2023 15:37:51 -0300 Message-ID: <20231204183751.64202-1-hiagofranco@gmail.com> X-Mailer: git-send-email 2.42.0 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Hiago De Franco Hi, I hope this email finds you well. I would like to ask a question regarding the usage of CDC NCM and VCN on an ARM device running the Linux kernel, connected to a host PC, also running Linux, via USB. I have successfully set up a CDC NCM connection, where my device acts as a DHCP server, and the connection is established without any issues. Now, I have a VNC server running on the device. However, when I connect to the VNC server, the performance is extremely slow and it also freezes, making it unusable. Interestingly, when I simultaneously launch iperf3 using the same NCM connection, the VNC performance improves significantly. The VNC remains smooth as long as iperf3 is active. When iperf3 finishes, the VNC returns to its frozen or slow state. I've tested the same setup with Windows 11, and in that case, the VNC operates normally without any issues. I've also compared the network traffic of both Windows and Linux connections using Wireshark but haven't identified anything relevant. Has anyone encountered a similar issue before? Could this be related to the size or quantity of transmitted packages? Any insights or assistance on this matter would be greatly appreciated. Thanks, Hiago