* Re: [net-next PATCH] via-velocity: Enable scatter/gather IO by default
2010-02-11 15:39 [net-next PATCH] via-velocity: Enable scatter/gather IO by default Simon Kagstrom
@ 2010-02-17 0:20 ` David Miller
2010-02-17 6:19 ` Simon Kagstrom
2010-02-18 0:01 ` David Miller
1 sibling, 1 reply; 5+ messages in thread
From: David Miller @ 2010-02-17 0:20 UTC (permalink / raw)
To: simon.kagstrom; +Cc: netdev, krkumar2
From: Simon Kagstrom <simon.kagstrom@netinsight.net>
Date: Thu, 11 Feb 2010 16:39:55 +0100
> Reduces CPU utilization significantly with sendfile for example.
>
> Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
I think you need to have a look at this patch before making
a change like this:
commit 83c98a8cd04dd0f848574370594886ba3bf56750
Author: Dave Jones <davej@redhat.com>
Date: Tue Jul 21 09:15:49 2009 +0000
Remove unused zero-copy code from velocity NIC driver.
This code hasn't been enabled in forever.
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/via-velocity.c b/drivers/net/via-velocity.c
index 42365e5..4ebe2ca 100644
--- a/drivers/net/via-velocity.c
+++ b/drivers/net/via-velocity.c
@@ -976,9 +976,6 @@ static int __devinit velocity_found1(struct pci_dev *pdev, const struct pci_devi
dev->netdev_ops = &velocity_netdev_ops;
dev->ethtool_ops = &velocity_ethtool_ops;
-#ifdef VELOCITY_ZERO_COPY_SUPPORT
- dev->features |= NETIF_F_SG;
-#endif
dev->features |= NETIF_F_HW_VLAN_TX | NETIF_F_HW_VLAN_FILTER |
NETIF_F_HW_VLAN_RX;
@@ -1849,11 +1846,7 @@ static void velocity_free_tx_buf(struct velocity_info *vptr, struct velocity_td_
pktlen = max_t(unsigned int, skb->len, ETH_ZLEN);
for (i = 0; i < tdinfo->nskb_dma; i++) {
-#ifdef VELOCITY_ZERO_COPY_SUPPORT
- pci_unmap_single(vptr->pdev, tdinfo->skb_dma[i], le16_to_cpu(td->tdesc1.len), PCI_DMA_TODEVICE);
-#else
pci_unmap_single(vptr->pdev, tdinfo->skb_dma[i], pktlen, PCI_DMA_TODEVICE);
-#endif
tdinfo->skb_dma[i] = 0;
}
}
@@ -2095,13 +2088,6 @@ static int velocity_xmit(struct sk_buff *skb, struct net_device *dev)
len = cpu_to_le16(pktlen);
-#ifdef VELOCITY_ZERO_COPY_SUPPORT
- if (skb_shinfo(skb)->nr_frags > 6 && __skb_linearize(skb)) {
- kfree_skb(skb);
- return NETDEV_TX_OK;
- }
-#endif
-
spin_lock_irqsave(&vptr->lock, flags);
index = vptr->tx.curr[qnum];
@@ -2111,59 +2097,18 @@ static int velocity_xmit(struct sk_buff *skb, struct net_device *dev)
td_ptr->tdesc1.TCR = TCR0_TIC;
td_ptr->td_buf[0].size &= ~TD_QUEUE;
-#ifdef VELOCITY_ZERO_COPY_SUPPORT
- if (skb_shinfo(skb)->nr_frags > 0) {
- int nfrags = skb_shinfo(skb)->nr_frags;
- tdinfo->skb = skb;
- if (nfrags > 6) {
- skb_copy_from_linear_data(skb, tdinfo->buf, skb->len);
- tdinfo->skb_dma[0] = tdinfo->buf_dma;
- td_ptr->tdesc0.len = len;
- td_ptr->tx.buf[0].pa_low = cpu_to_le32(tdinfo->skb_dma[0]);
- td_ptr->tx.buf[0].pa_high = 0;
- td_ptr->tx.buf[0].size = len; /* queue is 0 anyway */
- tdinfo->nskb_dma = 1;
- } else {
- int i = 0;
- tdinfo->nskb_dma = 0;
- tdinfo->skb_dma[i] = pci_map_single(vptr->pdev, skb->data,
- skb_headlen(skb), PCI_DMA_TODEVICE);
-
- td_ptr->tdesc0.len = len;
-
- /* FIXME: support 48bit DMA later */
- td_ptr->tx.buf[i].pa_low = cpu_to_le32(tdinfo->skb_dma);
- td_ptr->tx.buf[i].pa_high = 0;
- td_ptr->tx.buf[i].size = cpu_to_le16(skb_headlen(skb));
-
- for (i = 0; i < nfrags; i++) {
- skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
- void *addr = (void *)page_address(frag->page) + frag->page_offset;
-
- tdinfo->skb_dma[i + 1] = pci_map_single(vptr->pdev, addr, frag->size, PCI_DMA_TODEVICE);
-
- td_ptr->tx.buf[i + 1].pa_low = cpu_to_le32(tdinfo->skb_dma[i + 1]);
- td_ptr->tx.buf[i + 1].pa_high = 0;
- td_ptr->tx.buf[i + 1].size = cpu_to_le16(frag->size);
- }
- tdinfo->nskb_dma = i - 1;
- }
+ /*
+ * Map the linear network buffer into PCI space and
+ * add it to the transmit ring.
+ */
+ tdinfo->skb = skb;
+ tdinfo->skb_dma[0] = pci_map_single(vptr->pdev, skb->data, pktlen, PCI_DMA_TODEVICE);
+ td_ptr->tdesc0.len = len;
+ td_ptr->td_buf[0].pa_low = cpu_to_le32(tdinfo->skb_dma[0]);
+ td_ptr->td_buf[0].pa_high = 0;
+ td_ptr->td_buf[0].size = len;
+ tdinfo->nskb_dma = 1;
- } else
-#endif
- {
- /*
- * Map the linear network buffer into PCI space and
- * add it to the transmit ring.
- */
- tdinfo->skb = skb;
- tdinfo->skb_dma[0] = pci_map_single(vptr->pdev, skb->data, pktlen, PCI_DMA_TODEVICE);
- td_ptr->tdesc0.len = len;
- td_ptr->td_buf[0].pa_low = cpu_to_le32(tdinfo->skb_dma[0]);
- td_ptr->td_buf[0].pa_high = 0;
- td_ptr->td_buf[0].size = len;
- tdinfo->nskb_dma = 1;
- }
td_ptr->tdesc1.cmd = TCPLS_NORMAL + (tdinfo->nskb_dma + 1) * 16;
if (vptr->vlgrp && vlan_tx_tag_present(skb)) {
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