r8169: use 50% less ram for RX ring
Eric Dumazet [Mon, 11 Oct 2010 11:17:47 +0000 (11:17 +0000)]
Using standard skb allocations in r8169 leads to order-3 allocations (if
PAGE_SIZE=4096), because NIC needs 16383 bytes, and skb overhead makes
this bigger than 16384 -> 32768 bytes per "skb"

Using kmalloc() permits to reduce memory requirements of one r8169 nic
by 4Mbytes. (256 frames * 16Kbytes). This is fine since a hardware bug
requires us to copy incoming frames, so we build real skb when doing
this copy.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/r8169.c

index bc669a4..1760533 100644 (file)
@@ -187,12 +187,7 @@ static DEFINE_PCI_DEVICE_TABLE(rtl8169_pci_tbl) = {
 
 MODULE_DEVICE_TABLE(pci, rtl8169_pci_tbl);
 
-/*
- * we set our copybreak very high so that we don't have
- * to allocate 16k frames all the time (see note in
- * rtl8169_open()
- */
-static int rx_copybreak = 16383;
+static int rx_buf_sz = 16383;
 static int use_dac;
 static struct {
        u32 msg_enable;
@@ -484,10 +479,8 @@ struct rtl8169_private {
        struct RxDesc *RxDescArray;     /* 256-aligned Rx descriptor ring */
        dma_addr_t TxPhyAddr;
        dma_addr_t RxPhyAddr;
-       struct sk_buff *Rx_skbuff[NUM_RX_DESC]; /* Rx data buffers */
+       void *Rx_databuff[NUM_RX_DESC]; /* Rx data buffers */
        struct ring_info tx_skb[NUM_TX_DESC];   /* Tx data buffers */
-       unsigned align;
-       unsigned rx_buf_sz;
        struct timer_list timer;
        u16 cp_cmd;
        u16 intr_event;
@@ -515,8 +508,6 @@ struct rtl8169_private {
 
 MODULE_AUTHOR("Realtek and the Linux r8169 crew <netdev@vger.kernel.org>");
 MODULE_DESCRIPTION("RealTek RTL-8169 Gigabit Ethernet driver");
-module_param(rx_copybreak, int, 0);
-MODULE_PARM_DESC(rx_copybreak, "Copy breakpoint for copy-only-tiny-frames");
 module_param(use_dac, int, 0);
 MODULE_PARM_DESC(use_dac, "Enable PCI DAC. Unsafe on 32 bit PCI slot.");
 module_param_named(debug, debug.msg_enable, int, 0);
@@ -3196,7 +3187,6 @@ rtl8169_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
        dev->features |= NETIF_F_GRO;
 
        tp->intr_mask = 0xffff;
-       tp->align = cfg->align;
        tp->hw_start = cfg->hw_start;
        tp->intr_event = cfg->intr_event;
        tp->napi_event = cfg->napi_event;
@@ -3266,18 +3256,6 @@ static void __devexit rtl8169_remove_one(struct pci_dev *pdev)
        pci_set_drvdata(pdev, NULL);
 }
 
-static void rtl8169_set_rxbufsize(struct rtl8169_private *tp,
-                                 unsigned int mtu)
-{
-       unsigned int max_frame = mtu + VLAN_ETH_HLEN + ETH_FCS_LEN;
-
-       if (max_frame != 16383)
-               printk(KERN_WARNING PFX "WARNING! Changing of MTU on this "
-                       "NIC may lead to frame reception errors!\n");
-
-       tp->rx_buf_sz = (max_frame > RX_BUF_SIZE) ? max_frame : RX_BUF_SIZE;
-}
-
 static int rtl8169_open(struct net_device *dev)
 {
        struct rtl8169_private *tp = netdev_priv(dev);
@@ -3287,18 +3265,6 @@ static int rtl8169_open(struct net_device *dev)
        pm_runtime_get_sync(&pdev->dev);
 
        /*
-        * Note that we use a magic value here, its wierd I know
-        * its done because, some subset of rtl8169 hardware suffers from
-        * a problem in which frames received that are longer than
-        * the size set in RxMaxSize register return garbage sizes
-        * when received.  To avoid this we need to turn off filtering,
-        * which is done by setting a value of 16383 in the RxMaxSize register
-        * and allocating 16k frames to handle the largest possible rx value
-        * thats what the magic math below does.
-        */
-       rtl8169_set_rxbufsize(tp, 16383 - VLAN_ETH_HLEN - ETH_FCS_LEN);
-
-       /*
         * Rx and Tx desscriptors needs 256 bytes alignment.
         * dma_alloc_coherent provides more.
         */
@@ -3474,7 +3440,7 @@ static void rtl_hw_start_8169(struct net_device *dev)
 
        RTL_W8(EarlyTxThres, EarlyTxThld);
 
-       rtl_set_rx_max_size(ioaddr, tp->rx_buf_sz);
+       rtl_set_rx_max_size(ioaddr, rx_buf_sz);
 
        if ((tp->mac_version == RTL_GIGA_MAC_VER_01) ||
            (tp->mac_version == RTL_GIGA_MAC_VER_02) ||
@@ -3735,7 +3701,7 @@ static void rtl_hw_start_8168(struct net_device *dev)
 
        RTL_W8(EarlyTxThres, EarlyTxThld);
 
-       rtl_set_rx_max_size(ioaddr, tp->rx_buf_sz);
+       rtl_set_rx_max_size(ioaddr, rx_buf_sz);
 
        tp->cp_cmd |= RTL_R16(CPlusCmd) | PktCntrDisable | INTT_1;
 
@@ -3915,7 +3881,7 @@ static void rtl_hw_start_8101(struct net_device *dev)
 
        RTL_W8(EarlyTxThres, EarlyTxThld);
 
-       rtl_set_rx_max_size(ioaddr, tp->rx_buf_sz);
+       rtl_set_rx_max_size(ioaddr, rx_buf_sz);
 
        tp->cp_cmd |= rtl_rw_cpluscmd(ioaddr) | PCIMulRW;
 
@@ -3956,8 +3922,6 @@ static int rtl8169_change_mtu(struct net_device *dev, int new_mtu)
 
        rtl8169_down(dev);
 
-       rtl8169_set_rxbufsize(tp, dev->mtu);
-
        ret = rtl8169_init_ring(dev);
        if (ret < 0)
                goto out;
@@ -3978,15 +3942,15 @@ static inline void rtl8169_make_unusable_by_asic(struct RxDesc *desc)
        desc->opts1 &= ~cpu_to_le32(DescOwn | RsvdMask);
 }
 
-static void rtl8169_free_rx_skb(struct rtl8169_private *tp,
-                               struct sk_buff **sk_buff, struct RxDesc *desc)
+static void rtl8169_free_rx_databuff(struct rtl8169_private *tp,
+                                    void **data_buff, struct RxDesc *desc)
 {
        struct pci_dev *pdev = tp->pci_dev;
 
-       dma_unmap_single(&pdev->dev, le64_to_cpu(desc->addr), tp->rx_buf_sz,
+       dma_unmap_single(&pdev->dev, le64_to_cpu(desc->addr), rx_buf_sz,
                         PCI_DMA_FROMDEVICE);
-       dev_kfree_skb(*sk_buff);
-       *sk_buff = NULL;
+       kfree(*data_buff);
+       *data_buff = NULL;
        rtl8169_make_unusable_by_asic(desc);
 }
 
@@ -4005,33 +3969,34 @@ static inline void rtl8169_map_to_asic(struct RxDesc *desc, dma_addr_t mapping,
        rtl8169_mark_to_asic(desc, rx_buf_sz);
 }
 
-static struct sk_buff *rtl8169_alloc_rx_skb(struct pci_dev *pdev,
+static inline void *rtl8169_align(void *data)
+{
+       return (void *)ALIGN((long)data, 16);
+}
+
+static struct sk_buff *rtl8169_alloc_rx_data(struct pci_dev *pdev,
                                            struct net_device *dev,
-                                           struct RxDesc *desc, int rx_buf_sz,
-                                           unsigned int align, gfp_t gfp)
+                                           struct RxDesc *desc)
 {
-       struct sk_buff *skb;
+       void *data;
        dma_addr_t mapping;
-       unsigned int pad;
+       int node = dev->dev.parent ? dev_to_node(dev->dev.parent) : -1;
 
-       pad = align ? align : NET_IP_ALIGN;
+       data = kmalloc_node(rx_buf_sz, GFP_KERNEL, node);
+       if (!data)
+               return NULL;
 
-       skb = __netdev_alloc_skb(dev, rx_buf_sz + pad, gfp);
-       if (!skb)
-               goto err_out;
-
-       skb_reserve(skb, align ? ((pad - 1) & (unsigned long)skb->data) : pad);
-
-       mapping = dma_map_single(&pdev->dev, skb->data, rx_buf_sz,
+       if (rtl8169_align(data) != data) {
+               kfree(data);
+               data = kmalloc_node(rx_buf_sz + 15, GFP_KERNEL, node);
+               if (!data)
+                       return NULL;
+       }
+       mapping = dma_map_single(&pdev->dev, rtl8169_align(data), rx_buf_sz,
                                 PCI_DMA_FROMDEVICE);
 
        rtl8169_map_to_asic(desc, mapping, rx_buf_sz);
-out:
-       return skb;
-
-err_out:
-       rtl8169_make_unusable_by_asic(desc);
-       goto out;
+       return data;
 }
 
 static void rtl8169_rx_clear(struct rtl8169_private *tp)
@@ -4039,8 +4004,8 @@ static void rtl8169_rx_clear(struct rtl8169_private *tp)
        unsigned int i;
 
        for (i = 0; i < NUM_RX_DESC; i++) {
-               if (tp->Rx_skbuff[i]) {
-                       rtl8169_free_rx_skb(tp, tp->Rx_skbuff + i,
+               if (tp->Rx_databuff[i]) {
+                       rtl8169_free_rx_databuff(tp, tp->Rx_databuff + i,
                                            tp->RxDescArray + i);
                }
        }
@@ -4052,21 +4017,21 @@ static u32 rtl8169_rx_fill(struct rtl8169_private *tp, struct net_device *dev,
        u32 cur;
 
        for (cur = start; end - cur != 0; cur++) {
-               struct sk_buff *skb;
+               void *data;
                unsigned int i = cur % NUM_RX_DESC;
 
                WARN_ON((s32)(end - cur) < 0);
 
-               if (tp->Rx_skbuff[i])
+               if (tp->Rx_databuff[i])
                        continue;
 
-               skb = rtl8169_alloc_rx_skb(tp->pci_dev, dev,
-                                          tp->RxDescArray + i,
-                                          tp->rx_buf_sz, tp->align, gfp);
-               if (!skb)
+               data = rtl8169_alloc_rx_data(tp->pci_dev, dev,
+                                            tp->RxDescArray + i);
+               if (!data) {
+                       rtl8169_make_unusable_by_asic(tp->RxDescArray + i);
                        break;
-
-               tp->Rx_skbuff[i] = skb;
+               }
+               tp->Rx_databuff[i] = data;
        }
        return cur - start;
 }
@@ -4088,7 +4053,7 @@ static int rtl8169_init_ring(struct net_device *dev)
        rtl8169_init_ring_indexes(tp);
 
        memset(tp->tx_skb, 0x0, NUM_TX_DESC * sizeof(struct ring_info));
-       memset(tp->Rx_skbuff, 0x0, NUM_RX_DESC * sizeof(struct sk_buff *));
+       memset(tp->Rx_databuff, 0x0, NUM_RX_DESC * sizeof(void *));
 
        if (rtl8169_rx_fill(tp, dev, 0, NUM_RX_DESC, GFP_KERNEL) != NUM_RX_DESC)
                goto err_out;
@@ -4473,27 +4438,23 @@ static inline void rtl8169_rx_csum(struct sk_buff *skb, u32 opts1)
                skb_checksum_none_assert(skb);
 }
 
-static inline bool rtl8169_try_rx_copy(struct sk_buff **sk_buff,
-                                      struct rtl8169_private *tp, int pkt_size,
-                                      dma_addr_t addr)
+static struct sk_buff *rtl8169_try_rx_copy(void *data,
+                                          struct rtl8169_private *tp,
+                                          int pkt_size,
+                                          dma_addr_t addr)
 {
        struct sk_buff *skb;
-       bool done = false;
-
-       if (pkt_size >= rx_copybreak)
-               goto out;
-
-       skb = netdev_alloc_skb_ip_align(tp->dev, pkt_size);
-       if (!skb)
-               goto out;
 
+       data = rtl8169_align(data);
        dma_sync_single_for_cpu(&tp->pci_dev->dev, addr, pkt_size,
                                PCI_DMA_FROMDEVICE);
-       skb_copy_from_linear_data(*sk_buff, skb->data, pkt_size);
-       *sk_buff = skb;
-       done = true;
-out:
-       return done;
+       prefetch(data);
+       skb = netdev_alloc_skb_ip_align(tp->dev, pkt_size);
+       if (skb)
+               memcpy(skb->data, data, pkt_size);
+       dma_sync_single_for_device(&tp->pci_dev->dev, addr, pkt_size,
+                                  PCI_DMA_FROMDEVICE);
+       return skb;
 }
 
 /*
@@ -4508,7 +4469,7 @@ static int rtl8169_rx_interrupt(struct net_device *dev,
                                void __iomem *ioaddr, u32 budget)
 {
        unsigned int cur_rx, rx_left;
-       unsigned int delta, count;
+       unsigned int count;
        int polling = (budget != ~(u32)0) ? 1 : 0;
 
        cur_rx = tp->cur_rx;
@@ -4537,12 +4498,11 @@ static int rtl8169_rx_interrupt(struct net_device *dev,
                                rtl8169_schedule_work(dev, rtl8169_reset_task);
                                dev->stats.rx_fifo_errors++;
                        }
-                       rtl8169_mark_to_asic(desc, tp->rx_buf_sz);
+                       rtl8169_mark_to_asic(desc, rx_buf_sz);
                } else {
-                       struct sk_buff *skb = tp->Rx_skbuff[entry];
+                       struct sk_buff *skb;
                        dma_addr_t addr = le64_to_cpu(desc->addr);
                        int pkt_size = (status & 0x00001FFF) - 4;
-                       struct pci_dev *pdev = tp->pci_dev;
 
                        /*
                         * The driver does not support incoming fragmented
@@ -4552,18 +4512,16 @@ static int rtl8169_rx_interrupt(struct net_device *dev,
                        if (unlikely(rtl8169_fragmented_frame(status))) {
                                dev->stats.rx_dropped++;
                                dev->stats.rx_length_errors++;
-                               rtl8169_mark_to_asic(desc, tp->rx_buf_sz);
+                               rtl8169_mark_to_asic(desc, rx_buf_sz);
                                continue;
                        }
 
-                       if (rtl8169_try_rx_copy(&skb, tp, pkt_size, addr)) {
-                               dma_sync_single_for_device(&pdev->dev, addr,
-                                       pkt_size, PCI_DMA_FROMDEVICE);
-                               rtl8169_mark_to_asic(desc, tp->rx_buf_sz);
-                       } else {
-                               dma_unmap_single(&pdev->dev, addr, tp->rx_buf_sz,
-                                                PCI_DMA_FROMDEVICE);
-                               tp->Rx_skbuff[entry] = NULL;
+                       skb = rtl8169_try_rx_copy(tp->Rx_databuff[entry],
+                                                 tp, pkt_size, addr);
+                       rtl8169_mark_to_asic(desc, rx_buf_sz);
+                       if (!skb) {
+                               dev->stats.rx_dropped++;
+                               continue;
                        }
 
                        rtl8169_rx_csum(skb, status);
@@ -4592,20 +4550,7 @@ static int rtl8169_rx_interrupt(struct net_device *dev,
        count = cur_rx - tp->cur_rx;
        tp->cur_rx = cur_rx;
 
-       delta = rtl8169_rx_fill(tp, dev, tp->dirty_rx, tp->cur_rx, GFP_ATOMIC);
-       if (!delta && count)
-               netif_info(tp, intr, dev, "no Rx buffer allocated\n");
-       tp->dirty_rx += delta;
-
-       /*
-        * FIXME: until there is periodic timer to try and refill the ring,
-        * a temporary shortage may definitely kill the Rx process.
-        * - disable the asic to try and avoid an overflow and kick it again
-        *   after refill ?
-        * - how do others driver handle this condition (Uh oh...).
-        */
-       if (tp->dirty_rx + NUM_RX_DESC == tp->cur_rx)
-               netif_emerg(tp, intr, dev, "Rx buffers exhausted\n");
+       tp->dirty_rx += count;
 
        return count;
 }