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authorEric Dumazet <eric.dumazet@gmail.com>2009-10-06 20:37:59 -0400
committerDavid S. Miller <davem@davemloft.net>2009-10-08 01:00:22 -0400
commitf86dcc5aa8c7908f2c287e7a211228df599e3e71 (patch)
tree1721c94d0254b337b0668b2e331771dfef4b142d /Documentation/kernel-parameters.txt
parent8a6dfd43d1891882f8ca05d73aa7735fb0edae3b (diff)
udp: dynamically size hash tables at boot time
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: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
-rw-r--r--Documentation/kernel-parameters.txt3
1 files changed, 3 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 6fa7292947e5..02df20be7764 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2589,6 +2589,9 @@ and is between 256 and 4096 characters. It is defined in the file
2589 uart6850= [HW,OSS] 2589 uart6850= [HW,OSS]
2590 Format: <io>,<irq> 2590 Format: <io>,<irq>
2591 2591
2592 uhash_entries= [KNL,NET]
2593 Set number of hash buckets for UDP/UDP-Lite connections
2594
2592 uhci-hcd.ignore_oc= 2595 uhci-hcd.ignore_oc=
2593 [USB] Ignore overcurrent events (default N). 2596 [USB] Ignore overcurrent events (default N).
2594 Some badly-designed motherboards generate lots of 2597 Some badly-designed motherboards generate lots of