Messages in this thread | | | Date | Sat, 12 Dec 2009 17:57:51 -0800 | Subject | Re: nfs broken in net-next? -- now in mainline -- bisected: d9f5950f90292f7cc42834338dfd5f44dc4cc4ca | From | Yinghai Lu <> |
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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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