• Eric Dumazet's avatar
    fib: RCU conversion of fib_lookup() · ebc0ffae
    Eric Dumazet authored
    fib_lookup() converted to be called in RCU protected context, no
    reference taken and released on a contended cache line (fib_clntref)
    
    fib_table_lookup() and fib_semantic_match() get an additional parameter.
    
    struct fib_info gets an rcu_head field, and is freed after an rcu grace
    period.
    
    Stress test :
    (Sending 160.000.000 UDP frames on same neighbour,
    IP route cache disabled, dual E5540 @2.53GHz,
    32bit kernel, FIB_HASH) (about same results for FIB_TRIE)
    
    Before patch :
    
    real	1m31.199s
    user	0m13.761s
    sys	23m24.780s
    
    After patch:
    
    real	1m5.375s
    user	0m14.997s
    sys	15m50.115s
    
    Before patch Profile :
    
    13044.00 15.4% __ip_route_output_key vmlinux
     8438.00 10.0% dst_destroy           vmlinux
     5983.00  7.1% fib_semantic_match    vmlinux
     5410.00  6.4% fib_rules_lookup      vmlinux
     4803.00  5.7% neigh_lookup          vmlinux
     4420.00  5.2% _raw_spin_lock        vmlinux
     3883.00  4.6% rt_set_nexthop        vmlinux
     3261.00  3.9% _raw_read_lock        vmlinux
     2794.00  3.3% fib_table_lookup      vmlinux
     2374.00  2.8% neigh_resolve_output  vmlinux
     2153.00  2.5% dst_alloc             vmlinux
     1502.00  1.8% _raw_read_lock_bh     vmlinux
     1484.00  1.8% kmem_cache_alloc      vmlinux
     1407.00  1.7% eth_header            vmlinux
     1406.00  1.7% ipv4_dst_destroy      vmlinux
     1298.00  1.5% __copy_from_user_ll   vmlinux
     1174.00  1.4% dev_queue_xmit        vmlinux
     1000.00  1.2% ip_output             vmlinux
    
    After patch Profile :
    
    13712.00 15.8% dst_destroy             vmlinux
     8548.00  9.9% __ip_route_output_key   vmlinux
     7017.00  8.1% neigh_lookup            vmlinux
     4554.00  5.3% fib_semantic_match      vmlinux
     4067.00  4.7% _raw_read_lock          vmlinux
     3491.00  4.0% dst_alloc               vmlinux
     3186.00  3.7% neigh_resolve_output    vmlinux
     3103.00  3.6% fib_table_lookup        vmlinux
     2098.00  2.4% _raw_read_lock_bh       vmlinux
     2081.00  2.4% kmem_cache_alloc        vmlinux
     2013.00  2.3% _raw_spin_lock          vmlinux
     1763.00  2.0% __copy_from_user_ll     vmlinux
     1763.00  2.0% ip_output               vmlinux
     1761.00  2.0% ipv4_dst_destroy        vmlinux
     1631.00  1.9% eth_header              vmlinux
     1440.00  1.7% _raw_read_unlock_bh     vmlinux
    
    Reference results, if IP route cache is enabled :
    
    real	0m29.718s
    user	0m10.845s
    sys	7m37.341s
    
    25213.00 29.5% __ip_route_output_key   vmlinux
     9011.00 10.5% dst_release             vmlinux
     4817.00  5.6% ip_push_pending_frames  vmlinux
     4232.00  5.0% ip_finish_output        vmlinux
     3940.00  4.6% udp_sendmsg             vmlinux
     3730.00  4.4% __copy_from_user_ll     vmlinux
     3716.00  4.4% ip_route_output_flow    vmlinux
     2451.00  2.9% __xfrm_lookup           vmlinux
     2221.00  2.6% ip_append_data          vmlinux
     1718.00  2.0% _raw_spin_lock_bh       vmlinux
     1655.00  1.9% __alloc_skb             vmlinux
     1572.00  1.8% sock_wfree              vmlinux
     1345.00  1.6% kfree                   vmlinux
    Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    ebc0ffae
fib_lookup.h 1.47 KB