On Fri, Sep 12, 2003 at 07:34:24PM +0200, Thomas Leske wrote: > Edgar Friendly wrote: > >let me get this clear, you're proposing to have nodes pretend they > >don't have data? This seems to have the downside of non-probabilistic > >caching (ending up throwing out more data from the network) > > The downside of non-probabilistic caching was not that the nodes always > put the data into their cache. This just caused data to be dropped > that was equally unimportant. Pcaching will drop the data, even if > there are still gigs of free space left in the data store.
No it won't. Well, only if you have a huge datastore. Pcaching only kicks in after the store is 90% full. > The problem was that the caching worked too well. Data may not seem > to be popular from a single nodes view, because the requests were > distributed amoung too many nodes. Because of that nodes dropped the > wrong data items. > > >as well as > >the downside of probabilistic caching (successful requests take longer > >to find data). > > Most of the time they will only take one hop more. > > >It does have the upside that unlike probabilistic > >caching, it won't make requests fail even when their path goes over a > >node that has seen the data recently, but I'm still not seeing the > >worth of this proposal. > > One can not decide beforehand, if caching data is good or bad. > If the node that you route to is overloaded or it considers the > data to be popular anyways, then dropping the data was a bad decision. > On the other hand if our node caches the data, this might cause > the data to be dropped on the node that is in the "shadow" of ours. > This is bad, if the network prefers routing to that node. > > The proposal postpones the decision. The node always caches the > data and propagates new requests for the data as unimportant. > The response tells it, if caching was a good decision. If not, > the node behaves as if it had not cached the data. Space on the node is finite. What is the point of caching it if you're only going to transfer it again? The only modification to pcaching that I've heard of that makes any sense would be to cache all stuff that was requested locally but ignore it if it is requested remotely. > > -- > Thomas Leske -- Matthew J Toseland - [EMAIL PROTECTED] Freenet Project Official Codemonkey - http://freenetproject.org/ ICTHUS - Nothing is impossible. Our Boss says so.
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