Messages in this thread | | | Date | Wed, 5 May 1999 15:09:58 +0200 (CEST) | Subject | Strange UDP behaviour in RPC (call for suggestions...) | From | Trond Myklebust <> |
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Hi everybody,
I've received reports which suggest that the UDP layer is being slow to deliver packets that have been received in certain cases. Typically, in the sunrpc layer, we're sending out requests, which time out, then suddenly an avalanche of UDP replies to the same request is being seen:
May 4 19:10:57 p08 kernel: RPC: 37750 xprt_transmit(f4461374) May 4 19:10:57 p08 kernel: RPC: 37750 call_timeout (minor timeo) May 4 19:10:57 p08 kernel: RPC: 37750 xprt_transmit(f4461374) May 4 19:10:59 p08 kernel: RPC: 37750 call_timeout (minor timeo) May 4 19:10:59 p08 kernel: RPC: 37750 xprt_transmit(f4461374) May 4 19:11:02 p08 kernel: RPC: 37750 call_timeout (minor timeo) May 4 19:11:02 p08 kernel: RPC: 37750 xprt_transmit(f4461374) May 4 19:11:02 p08 kernel: RPC: udp_data_ready... May 4 19:11:02 p08 kernel: RPC: udp_data_ready client c1aac000 May 4 19:11:02 p08 kernel: RPC: 37750 received reply May 4 19:11:02 p08 kernel: RPC: udp_data_ready... May 4 19:11:02 p08 kernel: RPC: udp_data_ready client c1aac000 May 4 19:11:02 p08 kernel: RPC: unknown XID f4461374 in reply. May 4 19:11:02 p08 kernel: RPC: udp_data_ready... May 4 19:11:02 p08 kernel: RPC: udp_data_ready client c1aac000 May 4 19:11:02 p08 kernel: RPC: unknown XID f4461374 in reply. May 4 19:11:02 p08 kernel: RPC: udp_data_ready... May 4 19:11:02 p08 kernel: RPC: udp_data_ready client c1aac000 May 4 19:11:02 p08 kernel: RPC: unknown XID f4461374 in reply.
To me, that suggests that the requests are being queued, but not sent until something triggers the sending. Does anybody have any suggestions as to what is needed?
NOTE: The kernel lock is being held in most of the sunrpc code, but bottom halves are meant to be enabled most of the time, so I would have thought things to be OK. I've requested a tcpdump for the above case: it would be interesting to compare the above with tcpdump timing information. If nobody is immediately able to tell what's wrong, I can post the tcpdump info as soon as I get it...
Cheers, Trond
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