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Message-Id: <20100904042820.2655.19704.sendpatchset@jupiter1-ltc-lp2.austin.ibm.com> Date: Fri, 03 Sep 2010 23:28:20 -0500 From: Santiago Leon <santil@...ux.vnet.ibm.com> To: netdev@...r.kernel.org Cc: brking@...ux.vnet.ibm.com, Santiago Leon <santil@...ux.vnet.ibm.com>, anton@...ba.org Subject: [patch 04/21] ibmveth: Add tx_copybreak Use the existing bounce buffer if we send a buffer under a certain size. This saves the overhead of a TCE map/unmap. I can't see any reason for the wmb() in the bounce buffer case, if we need a barrier it will be before we call h_send_logical_lan but we have nothing in the common case. Remove it. Signed-off-by: Anton Blanchard <anton@...ba.org> Signed-off-by: Santiago Leon <santil@...ux.vnet.ibm.com> --- Index: net-next-2.6/drivers/net/ibmveth.c =================================================================== --- net-next-2.6.orig//drivers/net/ibmveth.c 2010-09-03 22:18:42.000000000 -0500 +++ net-next-2.6/drivers/net/ibmveth.c 2010-09-03 22:18:43.000000000 -0500 @@ -117,6 +117,11 @@ MODULE_DESCRIPTION("IBM i/pSeries Virtua MODULE_LICENSE("GPL"); MODULE_VERSION(ibmveth_driver_version); +static unsigned int tx_copybreak __read_mostly = 128; +module_param(tx_copybreak, uint, 0644); +MODULE_PARM_DESC(tx_copybreak, + "Maximum size of packet that is copied to a new buffer on transmit"); + struct ibmveth_stat { char name[ETH_GSTRING_LEN]; int offset; @@ -931,17 +936,24 @@ static netdev_tx_t ibmveth_start_xmit(st buf[1] = 0; } - data_dma_addr = dma_map_single(&adapter->vdev->dev, skb->data, - skb->len, DMA_TO_DEVICE); - if (dma_mapping_error(&adapter->vdev->dev, data_dma_addr)) { - if (!firmware_has_feature(FW_FEATURE_CMO)) - ibmveth_error_printk("tx: unable to map xmit buffer\n"); + if (skb->len < tx_copybreak) { + used_bounce = 1; + } else { + data_dma_addr = dma_map_single(&adapter->vdev->dev, skb->data, + skb->len, DMA_TO_DEVICE); + if (dma_mapping_error(&adapter->vdev->dev, data_dma_addr)) { + if (!firmware_has_feature(FW_FEATURE_CMO)) + ibmveth_error_printk("tx: unable to map " + "xmit buffer\n"); + tx_map_failed++; + used_bounce = 1; + } + } + + if (used_bounce) { skb_copy_from_linear_data(skb, adapter->bounce_buffer, skb->len); desc.fields.address = adapter->bounce_buffer_dma; - tx_map_failed++; - used_bounce = 1; - wmb(); } else desc.fields.address = data_dma_addr; -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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