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SubjectRe: nfs broken in net-next? -- now in mainline -- bisected: d9f5950f90292f7cc42834338dfd5f44dc4cc4ca
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On Sat, Dec 12, 2009 at 5:05 PM, Yinghai Lu <yinghai@kernel.org> wrote:
>
> [f86dcc5aa8c7908f2c287e7a211228df599e3e71] udp: dynamically
> size hash tables at boot time

commit f86dcc5aa8c7908f2c287e7a211228df599e3e71
Author: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed Oct 7 00:37:59 2009 +0000
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>

cause the problem: nfs mount fail.

the setup is:
64bit kernel, have all needed drivers in kernel, and boot with
ip=dhcp, root disk is 256M ramdisk.
then try to mount nfs....
YH


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