Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:49215 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753498AbbLPUrd (ORCPT ); Wed, 16 Dec 2015 15:47:33 -0500 Message-ID: <5671CDBD.5060006@codeaurora.org> (sfid-20151216_214736_598569_5ED012D4) Date: Wed, 16 Dec 2015 12:46:53 -0800 From: Peter Oh MIME-Version: 1.0 To: Felix Fietkau , Peter Oh , ath10k@lists.infradead.org CC: linux-wireless@vger.kernel.org Subject: Re: [PATCH] ath10k: add modparam 'hw_csum' to make HW checksum configurable References: <1450290051-15593-1-git-send-email-poh@qca.qualcomm.com> <5671AD10.70004@openwrt.org> <5671C99A.703@codeaurora.org> <5671CAF5.6010606@openwrt.org> In-Reply-To: <5671CAF5.6010606@openwrt.org> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 12/16/2015 12:35 PM, Felix Fietkau wrote: > On 2015-12-16 21:29, Peter Oh wrote: >> On 12/16/2015 10:27 AM, Felix Fietkau wrote: >>> On 2015-12-16 19:20, Peter Oh wrote: >>>> Some hardwares such as QCA988X and QCA99X0 doesn't have >>>> capability of checksum offload when frame formats are not >>>> suitable for it such as Mesh frame. >>>> Hence add a module parameter, hw_csum, to make checksum offload >>>> configurable during module registration time. >>>> >>>> Signed-off-by: Peter Oh >>> How about instead of inventing yet another crappy module parameter, you >>> call skb_checksum_help() in the driver in cases where the hardware is >>> unable to offload the checksum calculation. >>> >>> That way the user has to worry about less driver specific hackery ;) >> That will be good option for hardware not supporting HW checksum, but I >> mind that using the function will add more workload per every packet on >> critical data path when HW supports checksum resulting in throughput down. > I didn't mean calling it for every single frame in the data path. > What I'm suggesting is calling it selectively only for mesh frames, or > any other frames that the hardware cannot offload, and leaving the rest > for the hardware to process. > > There should be no performance difference between disabling checksum > offload and calling skb_checksum_help from the driver. To call it selectively for Mesh frame or interface, we need to add it on mac80211 layer such as ieee80211_build_hdr() since driver layer does not care the interface type in data path. In that case it will also introduce throughput degrade to HW that supports HW checksum for Mesh. > - Felix > -- > To unsubscribe from this list: send the line "unsubscribe linux-wireless" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Thanks, Peter