From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752825AbaEWPoG (ORCPT ); Fri, 23 May 2014 11:44:06 -0400 Received: from g4t3427.houston.hp.com ([15.201.208.55]:48807 "EHLO g4t3427.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752701AbaEWPoF (ORCPT ); Fri, 23 May 2014 11:44:05 -0400 Message-ID: <537F6CC1.2000503@hp.com> Date: Fri, 23 May 2014 08:44:01 -0700 From: Rick Jones User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: =?UTF-8?B?QmrDuHJuIE1vcms=?= , Jim Baxter CC: David Miller , eric.dumazet@gmail.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kamal@canonical.com, edumazet@google.com, mszeredi@suse.cz, fw@strlen.de Subject: Re: skbuff truesize incorrect. References: <537E4AFD.20304@mentor.com> <1400792295.5367.174.camel@edumazet-glaptop2.roam.corp.google.com> <1400792601.5367.176.camel@edumazet-glaptop2.roam.corp.google.com> <20140522.171033.1040508444998374401.davem@davemloft.net> <87ppj5vupf.fsf@nemi.mork.no> <537F0DCA.6030901@mentor.com> <87vbsw4z5x.fsf@nemi.mork.no> In-Reply-To: <87vbsw4z5x.fsf@nemi.mork.no> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/23/2014 02:33 AM, Bjørn Mork wrote: > Jim Baxter writes: > >>> I'll create and test a patch for the cdc_ncm host driver unless someone >>> else wants to do that. I haven't really played with the gadget driver >>> before, so I'd prefer if someone knowing it (Jim maybe?) could take care >>> of it. If not, then I can always make an attempt using dummy_hcd to >>> test it. >> I can create a patch for the host driver, I will issue the gadget patch >> first to resolve any issues, the fix would be similar. > > Well, I couldn't help myself. I just had to test it. The attached > patch works for me, briefly tested with an Ericsson H5321gw NCM device. > I have no ideas about the performance impact as that modem is limited to > 21 Mbps HSDPA. If you are measuring performance with the likes of netperf, you should be able to get an idea of the performance effect from the change in service demand (CPU consumed per unit of work) even if the maximum throughput remains capped. You can run a netperf TCP_STREAM test along the lines of: netperf -H -c -C -t TCP_STREAM and also netperf -H -c -C -t TCP_RR For extra added credit you can consider either multiple runs and post-processing, or adding a -i 30,3 to the command line to tell netperf to run at least three iterations, no more than thirty and it will try to achieve a 99% confidence that the reported means for throughput, local and remote CPU utilization are within +/- 2.5% of the actual mean. You can narrow or widen that with a -I 99,. A width of 5% is what gives the +/- 2.5% (and/or demonstrates my lack of accurate statistics knowledge :) ) happy benchmarking, rick jones