Re: NFS in Linux 2.2.1

Olaf Kirch (okir@monad.swb.de)
Tue, 02 Feb 1999 09:47:36 +0100


On 02 Feb 1999 00:45:51 +0100, Trond Myklebust wrote:
> It could be related to the RPC congestion avoidance algorithm. It
> reduces the number of available RPC slots far too rapidly in my
> opinion, halving the number of free slots for each message
> timeout. This would certainly fit the numbers you quote.

This is the standard mode of operation. The number of biods you run
on on other Unices has no impact on the max number of concurrent requests;
they just define the max number of concurrent async requests. Congestion
avoidance still takes place, and can go down to one.

As a rule of thumb, whenever the congestion avoidance algorithm gives
you problems, either your network or server is overloaded, or the
_max_ congestion window is too big. You shouldn't be seeing timeouts
on a big scale during normal operations at all. If you do, and try
to remedy the situation by increasing the network load even more (by
bumping the min congestion window) you usually make things worse.

Olaf

-- 
Olaf Kirch         |  --- o --- Nous sommes du soleil we love when we play
okir@monad.swb.de  |    / | \   sol.dhoop.naytheet.ah kin.ir.samse.qurax

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