Return-path: Received: from mail.candelatech.com ([208.74.158.172]:54088 "EHLO ns3.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751640Ab1AIRtO (ORCPT ); Sun, 9 Jan 2011 12:49:14 -0500 Message-ID: <4D29F512.3050707@candelatech.com> Date: Sun, 09 Jan 2011 09:49:06 -0800 From: Ben Greear MIME-Version: 1.0 To: Gabor Juhos CC: linux-wireless@vger.kernel.org, ath9k-devel@venema.h4ckr.net Subject: Re: [PATCH] ath9k: Implement rx copy-break. References: <1294500800-29191-1-git-send-email-greearb@candelatech.com> <4D296B12.8000801@openwrt.org> In-Reply-To: <4D296B12.8000801@openwrt.org> Content-Type: text/plain; charset=ISO-8859-2; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 01/09/2011 12:00 AM, Gabor Juhos wrote: > Hi Ben, > >> From: Ben Greear >> >> This saves us constantly allocating large, multi-page >> skbs. It should fix the order-1 allocation errors reported, >> and in a 60-vif scenario, this significantly decreases CPU >> utilization, and latency, and increases bandwidth. >> >> Signed-off-by: Ben Greear >> --- >> :100644 100644 b2497b8... ea2f67c... M drivers/net/wireless/ath/ath9k/recv.c >> drivers/net/wireless/ath/ath9k/recv.c | 92 ++++++++++++++++++++++----------- >> 1 files changed, 61 insertions(+), 31 deletions(-) > > <...> > >> + if (use_copybreak) { >> + struct pci_dev *pdev = to_pci_dev(sc->dev); > > This would cause undefined behaviour with ath9k devices sitting on an AHB bus. > >> + pci_dma_sync_single_for_cpu(pdev, bf->bf_buf_addr, >> + len, PCI_DMA_FROMDEVICE); >> + skb_copy_from_linear_data(bf->bf_mpdu, skb->data, len); >> + pci_dma_sync_single_for_device(pdev, bf->bf_buf_addr, >> + len, PCI_DMA_FROMDEVICE); > > Please use the bus agnostic equivalents of these DMA functions. Any idea what that might be? Should we just disable copybreak for things on AHB bus? Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com