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ixgbe: set max desc to prevent total RSC packet size of 64K 

The performance of hardware RSC is greatly reduced if the total for max rsc
descriptors multiplied by the buffer size is greater than 65535.  To
prevent this we need to adjust the max rsc descriptors appropriately.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Duyck 2009-05-17 20:57:47 +00:00 committed by David S. Miller
parent 82d048186e
commit e76678dd65
2 changed files with 20 additions and 11 deletions
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2
drivers/net/ixgbe/ixgbe.h
View File

@ -75,6 +75,8 @@
#define IXGBE_RXBUFFER_128 128 /* Used for packet split */
#define IXGBE_RXBUFFER_256 256 /* Used for packet split */
#define IXGBE_RXBUFFER_2048 2048
#define IXGBE_RXBUFFER_4096 4096
#define IXGBE_RXBUFFER_8192 8192
#define IXGBE_MAX_RXBUFFER 16384 /* largest size for a single descriptor */
#define IXGBE_RX_HDR_SIZE IXGBE_RXBUFFER_256

29
drivers/net/ixgbe/ixgbe_main.c
View File

@ -1995,21 +1995,28 @@ static void ixgbe_configure_rx(struct ixgbe_adapter *adapter)
rscctrl = IXGBE_READ_REG(hw, IXGBE_RSCCTL(j));
rscctrl |= IXGBE_RSCCTL_RSCEN;
/*
* if packet split is enabled we can only support up
* to max frags + 1 descriptors.
* we must limit the number of descriptors so that the
* total size of max desc * buf_len is not greater
* than 65535
*/
if (adapter->flags & IXGBE_FLAG_RX_PS_ENABLED)
#if (MAX_SKB_FRAGS < 3)
rscctrl |= IXGBE_RSCCTL_MAXDESC_1;
#elif (MAX_SKB_FRAGS < 7)
rscctrl |= IXGBE_RSCCTL_MAXDESC_4;
#elif (MAX_SKB_FRAGS < 15)
if (adapter->flags & IXGBE_FLAG_RX_PS_ENABLED) {
#if (MAX_SKB_FRAGS > 16)
rscctrl |= IXGBE_RSCCTL_MAXDESC_16;
#elif (MAX_SKB_FRAGS > 8)
rscctrl |= IXGBE_RSCCTL_MAXDESC_8;
#elif (MAX_SKB_FRAGS > 4)
rscctrl |= IXGBE_RSCCTL_MAXDESC_4;
#else
rscctrl |= IXGBE_RSCCTL_MAXDESC_16;
rscctrl |= IXGBE_RSCCTL_MAXDESC_1;
#endif
else
rscctrl |= IXGBE_RSCCTL_MAXDESC_16;
} else {
if (rx_buf_len < IXGBE_RXBUFFER_4096)
rscctrl |= IXGBE_RSCCTL_MAXDESC_16;
else if (rx_buf_len < IXGBE_RXBUFFER_8192)
rscctrl |= IXGBE_RSCCTL_MAXDESC_8;
else
rscctrl |= IXGBE_RSCCTL_MAXDESC_4;
}
IXGBE_WRITE_REG(hw, IXGBE_RSCCTL(j), rscctrl);
}
/* Disable RSC for ACK packets */