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r8169: use 50% less ram for RX ring
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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>
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Eric Dumazet authored and David S. Miller committed Oct 16, 2010
1 parent 7662ff4 commit 6f0333b
Showing 1 changed file with 64 additions and 119 deletions.
183 changes: 64 additions & 119 deletions drivers/net/r8169.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand All @@ -3286,18 +3264,6 @@ 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.
Expand Down Expand Up @@ -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) ||
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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;
Expand All @@ -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);
}

Expand All @@ -4005,42 +3969,43 @@ 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)
{
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);
}
}
Expand All @@ -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;
}
Expand All @@ -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;
Expand Down Expand Up @@ -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;
}

/*
Expand All @@ -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;
Expand Down Expand Up @@ -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
Expand All @@ -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);
Expand Down Expand Up @@ -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;
}
Expand Down

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