Messages in this thread | | | Date | Tue, 23 Jan 2001 00:00:29 +0100 (CET) | Subject | Re: [NFS] [CFT] Improved RPC congestion handling for 2.4.0 (and 2.2.18) | From | Trond Myklebust <> |
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>>>>> " " == H J Lu <hjl@valinux.com> writes:
> I got a report which indicates it may not be a good idea, > especially for UDP. Suppose you have a lousy LAN or NFS UDP > server for whatever reason, some NFS/UDP packets may get lost > very easily while a ping request may get through. In that case, > the rpc ping may slow down the NFS client over UDP > significantly.
Hi HJ,
Could you clarify this? Don't forget that we only send the ping after a major timeout (usually after 3 or more resends).
IOW: If the ping gets through, then it'll have cost us 1 RPC request, which is hardly a major contribution when talking about timescales of the order of 5 seconds which is what that major timeout will have cost (Don't forget that RPC timeout values increase geometrically).
I'm not touting this as a cure for incorrect rsize/wsize settings. I use it rather to avoid false 'server is not responding' due to server congestion. On the current RPC code, the latter can occur sometimes even with a loopback NFS mount when, say, kflushd is busy hogging the disk...
Cheers, Trond - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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