From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH net-next v2 05/10] net: qualcomm: rmnet: Set pacing rate Date: Wed, 03 Jan 2018 23:44:50 -0800 Message-ID: <1515051890.131759.6.camel@gmail.com> References: <1515015787-6713-1-git-send-email-subashab@codeaurora.org> <1515015787-6713-6-git-send-email-subashab@codeaurora.org> <1515016918.131759.2.camel@gmail.com> <8bd76556945c563980a72009f9c86a13@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, netdev@vger.kernel.org, lkp@intel.com To: Subash Abhinov Kasiviswanathan Return-path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:39015 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752371AbeADHoz (ORCPT ); Thu, 4 Jan 2018 02:44:55 -0500 Received: by mail-wm0-f66.google.com with SMTP id i11so1701387wmf.4 for ; Wed, 03 Jan 2018 23:44:54 -0800 (PST) In-Reply-To: <8bd76556945c563980a72009f9c86a13@codeaurora.org> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2018-01-03 at 15:45 -0700, Subash Abhinov Kasiviswanathan wrote: > > > + sk_pacing_shift_update(skb->sk, 8); > > > > Well... Please tell us why this is needed in this driver. > > > > This interface is meant for wifi aggregation, not to work around some > > strange ethernet drivers designs. > > Hi Eric > > The real device over which the rmnet devices are installed also > aggregate multiple IP packets and sends them as a single large aggregate > frame to the hardware. It would be nice to give some details about this in the changelog. Also what results you get with different values for the shift (10, 9, 8) My fear is that people might be tempted to blindly use the sk_pacing_shift_update() just because a single TCP flow gets 'better' results. bufferbloat is a serious issue, we do not want to allow a single TCP flow to fill a fifo. Otherwise, we could remove TCP Small queues overhead from the kernel and be happy. Thanks.