Maintained by: NLnet Labs

[Unbound-users] Improve avg response times

Stephan Lagerholm
Mon Jul 9 15:34:43 CEST 2012


Hi Vinay,

 

The unbound name server is using the Least resent used (LRU) algorithm
to decide what to throw out when the cache gets full. There is no
'garbage collection' like in Bind. Doing this like unbound does it
should be somewhat faster and nicer to the processor, but the flip-side
is that prefetching is not working that very well (good stuff might get
thrown out when prefetching). 

 

I notice that you don't have that much memory. Maybe your memory is only
large enough for say 10 minutes of cached entries. If nobody is asking
for www.utorrent.com during those 10 minutes, then it will be kicked
out. Try to increase your cache memory size or ask more often for the
site that you want to make sure you have cached.

 

/Stephan

 

 

 

From: unbound-users-bounces at unbound.net
[mailto:unbound-users-bounces at unbound.net] On Behalf Of
vinay3 at justemail.net
Sent: Saturday, July 07, 2012 1:55 PM
To: unbound-users at unbound.net
Subject: Re: [Unbound-users] Improve avg response times

 

I tried using a prefetch trigger at 90% instead of 10% (intentionally
inefficient) and a cache-min-ttl of 5400 so that an hourly scan is
guaranteed to find a cached entry from the last scan and will also reset
it's TTL back to 5400 by forcing a new iteration.

 

If I do a new namebench run, I still get a 150ms+ avg response time and
I see several responses that have a TTL of 5400 meaning they were
cachemisses. 

 

blog.sina.com.cn.

A

814.8959

5400

2

blogx.sina.com.cn. -> 218.30.115.254

	
	

www.utorrent.com.

A

203.908

5400

1

67.215.233.130

			
	

in.youtube.com.

A

29.46731

2982

2

youtube-ui.l.google.com. -> 74.125.224.46, 74.125.224.32, 74.125.224.33,
74.125.224.34, 74.125.224.35, 74.125.224.36, 74.125.224.37,
74.125.224.38, 74.125.224.39, 74.125.224.40, 74.125.224.41

	

search.mywebsearch.com.

A

72.6796

2985

2

www154.mywebsearch.com. -> 74.113.233.48

	

wenwen.soso.com.

A

296.7475

5236

1

202.55.10.153

			
	

www.uploading.com.

A

26.0509

3007

1

195.191.207.40

			
	

www.ebay.com.

A

31.4418

5400

1

66.135.200.161, 66.135.200.181, 66.135.210.61, 66.135.210.181,
66.211.181.161, 66.211.181.181

 

So this is appearing like unexpected behavior to me: If www.utorrent.com
was scanned less than an hour ago and was supposed to be cached for 5400
seconds, why would a random scan like the one above find it flushed out
of the cache (5400 TTL) and requiring an iteration (203.9 msecs response
time)?

 

 

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