Lime Group Lime Group homeaboutdownloadsupportpresscontact
Download LimeWire Now!
Statistics
Current Hosts:
04/30/01 - 05:00pm
News
Lime Wire proudly announces the release of LimeWire 1.3
LimeWire
Preliminary Caching Results

Objective


Study the feasibility of introducing caching queries and responses on hosts on the Gnutella network.

t o p

Methodology


We first “recorded” sample messages off the network. The recorder filtered out pings, pongs and pushes. So the sample only consisted of Queries and Responses. The messages were later “played-back” to a host that caches queries, and a hit count was calculated based on various cache-replacement algorithms.

The caching algorithm used makes a distinction between broad queries and specific queries. Broad queries are defined as queries that contain a wild card character or begin with a “.”. (A better implementation would have filtered queries like “mp3” and other commonly seen extensions).  The cache disregards broad queries. The reason is that if a broad query comes along, almost all entries in the cache would be appropriate responses.

t o p

Results


t o p

Comments

The results indicate that the best performance is achieved with the LRU replacement policy. But intuitively random replacement may be ideal since it prevents adjacent hosts from caching the same results. Perhaps a hybrid of replacement algorithms (like Random tending to FIFO) would be good.

Cache size is an important consideration. Even small caches can be a drain on the resources on memory for clients on the network. Another important consideration is that even if each host has a smaller cache size, the overall cache size of the network is the compounded size of all the caches in the network.

There can be some not so good behavior that results from caching. Consider the situation that a new host comes on to the network and wants to share files that other people may want to be able to access. If there is another host in the middle that caches results to which the new host would have (normally) responded.  In this situation caching the results has reduced the effectiveness of the network.

Given these problems and the general nature the traffic on the Gnutella network, perhaps it’s a good idea to invalidate entries in the cache that are more than 15 seconds old.

t o p

Comments and questions are welcome at sthadani@limepeer.com

t o p

home | about | download | support | resources | press | contact | legal | Terms of Use | Privacy Policy