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authorEric Dumazet <dada1@cosmosbay.com>2009-05-12 20:48:02 +0000
committerDavid S. Miller <davem@davemloft.net>2009-05-17 20:47:44 -0700
commitd62fda082c48b417b47a553860abf75d9cf8b591 (patch)
tree1b2679e4fcce72eb6ac584ecf9cc039fe9ea2c4a /drivers/isdn/gigaset
parent9dc20c5f78c53bf57fb7874b6e942842e1db20d3 (diff)
bnx2: bnx2_tx_int() optimizations
When using bnx2 in a high transmit load, bnx2_tx_int() cost is pretty high. There are two reasons. One is an expensive call to bnx2_get_hw_tx_cons(bnapi) for each freed skb One is cpu stalls when accessing skb_is_gso(skb) / skb_shinfo(skb)->nr_frags because of two cache line misses. (One to get skb->end/head to compute skb_shinfo(skb), one to get is_gso/nr_frags) This patch : 1) avoids calling bnx2_get_hw_tx_cons(bnapi) too many times. 2) makes bnx2_start_xmit() cache is_gso & nr_frags into sw_tx_bd descriptor. This uses a litle bit more ram (256 longs per device on x86), but helps a lot. 3) uses a prefetch(&skb->end) to speedup dev_kfree_skb(), bringing cache line that will be needed in skb_release_data() result is 5 % bandwidth increase in benchmarks, involving UDP or TCP receive & transmits, when a cpu is dedicated to ksoftirqd for bnx2. bnx2_tx_int going from 3.33 % cpu to 0.5 % cpu in oprofile Note : skb_dma_unmap() still very expensive but this is for another patch, not related to bnx2 (2.9 % of cpu, while it does nothing on x86_32) Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/isdn/gigaset')
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