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author | Eric Dumazet <dada1@cosmosbay.com> | 2008-11-14 00:53:54 -0800 |
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committer | David S. Miller <davem@davemloft.net> | 2008-11-14 00:53:54 -0800 |
commit | ef711cf1d156428d4c2911b8c86c6ce90519dc45 (patch) | |
tree | 3c5f5f34d70585d7bd2455f288fe7efe4b272710 /drivers/net/usb/pegasus.c | |
parent | f30ab418a1d3c5a8b83493e7d70d6876a74aa0ce (diff) | |
download | op-kernel-dev-ef711cf1d156428d4c2911b8c86c6ce90519dc45.zip op-kernel-dev-ef711cf1d156428d4c2911b8c86c6ce90519dc45.tar.gz |
net: speedup dst_release()
During tbench/oprofile sessions, I found that dst_release() was in third position.
CPU: Core 2, speed 2999.68 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask of 0x00 (Unhalted core cycles) count 100000
samples % symbol name
483726 9.0185 __copy_user_zeroing_intel
191466 3.5697 __copy_user_intel
185475 3.4580 dst_release
175114 3.2648 ip_queue_xmit
153447 2.8608 tcp_sendmsg
108775 2.0280 tcp_recvmsg
102659 1.9140 sysenter_past_esp
101450 1.8914 tcp_current_mss
95067 1.7724 __copy_from_user_ll
86531 1.6133 tcp_transmit_skb
Of course, all CPUS fight on the dst_entry associated with 127.0.0.1
Instead of first checking the refcount value, then decrement it,
we use atomic_dec_return() to help CPU to make the right memory transaction
(ie getting the cache line in exclusive mode)
dst_release() is now at the fifth position, and tbench a litle bit faster ;)
CPU: Core 2, speed 3000.1 MHz (estimated)
Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask of 0x00 (Unhalted core cycles) count 100000
samples % symbol name
647107 8.8072 __copy_user_zeroing_intel
258840 3.5229 ip_queue_xmit
258302 3.5155 __copy_user_intel
209629 2.8531 tcp_sendmsg
165632 2.2543 dst_release
149232 2.0311 tcp_current_mss
147821 2.0119 tcp_recvmsg
137893 1.8767 sysenter_past_esp
127473 1.7349 __copy_from_user_ll
121308 1.6510 ip_finish_output
118510 1.6129 tcp_transmit_skb
109295 1.4875 tcp_v4_rcv
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/usb/pegasus.c')
0 files changed, 0 insertions, 0 deletions