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    udp: dynamically size hash tables at boot time · f86dcc5a
    Eric Dumazet 提交于
    UDP_HTABLE_SIZE was initialy defined to 128, which is a bit small for
    several setups.
    
    4000 active UDP sockets -> 32 sockets per chain in average. An
    incoming frame has to lookup all sockets to find best match, so long
    chains hurt latency.
    
    Instead of a fixed size hash table that cant be perfect for every
    needs, let UDP stack choose its table size at boot time like tcp/ip
    route, using alloc_large_system_hash() helper
    
    Add an optional boot parameter, uhash_entries=x so that an admin can
    force a size between 256 and 65536 if needed, like thash_entries and
    rhash_entries.
    
    dmesg logs two new lines :
    [    0.647039] UDP hash table entries: 512 (order: 0, 4096 bytes)
    [    0.647099] UDP Lite hash table entries: 512 (order: 0, 4096 bytes)
    
    Maximal size on 64bit arches would be 65536 slots, ie 1 MBytes for non
    debugging spinlocks.
    Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
    Signed-off-by: NDavid S. Miller <davem@davemloft.net>
    f86dcc5a
udp.c 48.4 KB