diff options
Diffstat (limited to 'drivers/net/ethernet/ibm/ibmvnic.h')
| -rw-r--r-- | drivers/net/ethernet/ibm/ibmvnic.h | 45 |
1 files changed, 43 insertions, 2 deletions
diff --git a/drivers/net/ethernet/ibm/ibmvnic.h b/drivers/net/ethernet/ibm/ibmvnic.h index 7d430fdf47c0..178035872c32 100644 --- a/drivers/net/ethernet/ibm/ibmvnic.h +++ b/drivers/net/ethernet/ibm/ibmvnic.h @@ -36,9 +36,50 @@ #define IBMVNIC_TSO_BUFS 64 #define IBMVNIC_TSO_POOL_MASK 0x80000000 -#define IBMVNIC_MAX_LTB_SIZE ((1 << (MAX_ORDER - 1)) * PAGE_SIZE) -#define IBMVNIC_BUFFER_HLEN 500 +/* A VNIC adapter has set of Rx and Tx pools (aka queues). Each Rx/Tx pool + * has a set of buffers. The size of each buffer is determined by the MTU. + * + * Each Rx/Tx pool is also associated with a DMA region that is shared + * with the "hardware" (VIOS) and used to send/receive packets. The DMA + * region is also referred to as a Long Term Buffer or LTB. + * + * The size of the DMA region required for an Rx/Tx pool depends on the + * number and size (MTU) of the buffers in the pool. At the max levels + * of 4096 jumbo frames (MTU=9000) we will need about 9K*4K = 36MB plus + * some padding. + * + * But the size of a single DMA region is limited by MAX_ORDER in the + * kernel (about 16MB currently). To support say 4K Jumbo frames, we + * use a set of LTBs (struct ltb_set) per pool. + * + * IBMVNIC_ONE_LTB_MAX - max size of each LTB supported by kernel + * IBMVNIC_ONE_LTB_SIZE - current max size of each LTB in an ltb_set + * (must be <= IBMVNIC_ONE_LTB_MAX) + * IBMVNIC_LTB_SET_SIZE - current size of all LTBs in an ltb_set + * + * Each VNIC can have upto 16 Rx, 16 Tx and 16 TSO pools. The TSO pools + * are of fixed length (IBMVNIC_TSO_BUF_SZ * IBMVNIC_TSO_BUFS) of 4MB. + * + * The Rx and Tx pools can have upto 4096 buffers. The max size of these + * buffers is about 9588 (for jumbo frames, including IBMVNIC_BUFFER_HLEN). + * So, setting the IBMVNIC_LTB_SET_SIZE for a pool to 4096 * 9588 ~= 38MB. + * + * There is a trade-off in setting IBMVNIC_ONE_LTB_SIZE. If it is large, + * the allocation of the LTB can fail when system is low in memory. If + * its too small, we would need several mappings for each of the Rx/ + * Tx/TSO pools but there is a limit of 255 mappings per vnic in the + * VNIC protocol. + * + * So setting IBMVNIC_ONE_LTB_SIZE to 8MB. With IBMVNIC_LTB_SET_SIZE set + * to 38MB, we will need 5 LTBs per Rx and Tx pool and 1 LTB per TSO + * pool for the 4MB. Thus the 16 Rx and Tx queues require 32 * 5 = 160 + * plus 16 for the TSO pools for a total of 176 LTB mappings per VNIC. + */ +#define IBMVNIC_ONE_LTB_MAX ((u32)((1 << (MAX_ORDER - 1)) * PAGE_SIZE)) +#define IBMVNIC_ONE_LTB_SIZE min((u32)(8 << 20), IBMVNIC_ONE_LTB_MAX) +#define IBMVNIC_LTB_SET_SIZE (38 << 20) +#define IBMVNIC_BUFFER_HLEN 500 #define IBMVNIC_RESET_DELAY 100 static const char ibmvnic_priv_flags[][ETH_GSTRING_LEN] = { |