From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH 3/3] chelsio: more rx speedup Date: Tue, 9 Jan 2007 10:26:47 -0800 Message-ID: <20070109102647.05d92861@freekitty> References: <20061215190716.956791000@osdl.org> <20070108112524.730e89f0@dxpl.pdx.osdl.net> <20070108112612.5f947357@dxpl.pdx.osdl.net> <200701090942.04197.netdev@axxeo.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Jeff Garzik , netdev@vger.kernel.org Return-path: Received: from smtp.osdl.org ([65.172.181.24]:59630 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932148AbXAISbU (ORCPT ); Tue, 9 Jan 2007 13:31:20 -0500 To: Ingo Oeser In-Reply-To: <200701090942.04197.netdev@axxeo.de> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, 9 Jan 2007 09:42:03 +0100 Ingo Oeser wrote: > Hi Stephen, > > Stephen Hemminger schrieb: > > --- netdev-2.6.orig/drivers/net/chelsio/sge.c > > +++ netdev-2.6/drivers/net/chelsio/sge.c > [...] > > @@ -1043,45 +1046,42 @@ static void recycle_fl_buf(struct freelQ > > * be copied but there is no memory for the copy. > > */ > > static inline struct sk_buff *get_packet(struct pci_dev *pdev, > > - struct freelQ *fl, unsigned int len, > > - int dma_pad, int skb_pad, > > - unsigned int copy_thres, > > - unsigned int drop_thres) > > + struct freelQ *fl, unsigned int len) > > { > > struct sk_buff *skb; > > - struct freelQ_ce *ce = &fl->centries[fl->cidx]; > > + const struct freelQ_ce *ce = &fl->centries[fl->cidx]; > > > > - if (len < copy_thres) { > > - skb = alloc_skb(len + skb_pad, GFP_ATOMIC); > > - if (likely(skb != NULL)) { > > - skb_reserve(skb, skb_pad); > > - skb_put(skb, len); > > - pci_dma_sync_single_for_cpu(pdev, > > - pci_unmap_addr(ce, dma_addr), > > - pci_unmap_len(ce, dma_len), > > - PCI_DMA_FROMDEVICE); > > - memcpy(skb->data, ce->skb->data + dma_pad, len); > > - pci_dma_sync_single_for_device(pdev, > > + if (len < copybreak) { > > + skb = alloc_skb(len + 2, GFP_ATOMIC); > > + if (!skb) > > + goto use_orig_buf; > > + > > + skb_reserve(skb, 2); /* align IP header */ > > Please use NET_IP_ALIGN here: Wrong, NET_IP_ALIGN is intended to deal with platforms where alignment of DMA is more important of alignment of structures. Therefore if data is copied, it should always be 2. > > + skb = alloc_skb(len + NET_IP_ALIGN, GFP_ATOMIC); > + if (!skb) > + goto use_orig_buf; > + > + skb_reserve(skb, NET_IP_ALIGN); > > > + skb_put(skb, len); > > + pci_dma_sync_single_for_cpu(pdev, > > pci_unmap_addr(ce, dma_addr), > > pci_unmap_len(ce, dma_len), > > PCI_DMA_FROMDEVICE); > > - } else if (!drop_thres) > > - goto use_orig_buf; > > - > > + memcpy(skb->data, ce->skb->data, len); > > + pci_dma_sync_single_for_device(pdev, > > + pci_unmap_addr(ce, dma_addr), > > + pci_unmap_len(ce, dma_len), > > + PCI_DMA_FROMDEVICE); > > recycle_fl_buf(fl, fl->cidx); > > return skb; > > } > > > > - if (fl->credits < drop_thres) { > > +use_orig_buf: > > + if (fl->credits < 2) { > > Why 2? What does this magic number mean? No idea, it was there in the original. (as a parameter). -- Stephen Hemminger