------- Original Msg -----
From: "RunxiaWan" <[email protected]>
Subject: Problem in Performance test
Hi all,
I am doing performance test for my company's resolver with BIND 9.10.3 and
find something weird. The test client and resolver are in the same LAN. When
I use a small set of domain as an input with a 10000 per second query
sending rate, everything looks reasonable. However, when I use a set of
thousands of domains as an input, The QPS is unexpectedly low and the
latency is high. Here is the result from DNSperf:
Queries sent: 11823
Queries completed: 11823 (100.00%)
Queries lost: 0 (0.00%)
Response codes: NOERROR 9883 (83.59%), SERVFAIL 242 (2.05%),
NXDOMAIN 1698 (14.36%)
Average packet size: request 48, response 203
Run time (s): 69.891567
Queries per second: 169.162039
Average Latency (s): 0.519502 (min 0.003766, max 211.981919)
Latency StdDev (s): 1.423057
And when I decreased the query sending rate to 100 per second, the latency
decrease as the same when I use small set of domain as an input. Here is the
result from DNSperf:
Statistics:
Queries sent: 6000
Queries completed: 6000 (100.00%)
Queries lost: 0 (0.00%)
Response codes: NOERROR 4995 (83.25%), SERVFAIL 37 (0.62%), NXDOMAIN
968 (16.13%)
Average packet size: request 54, response 211
Run time (s): 62.789257
Queries per second: 95.557748
Average Latency (s): 0.083028 (min 0.005266, max 134.543920)
Latency StdDev (s): 0.568863
Anyone knows any explanation for this? Thanks.
---------------
Runxia Wan(Brian)
Research Engineer
BII Lab
Beijing Internet Institute(BII)
[email protected]
---------------------------------------
Few things are affecting the resolver test:
1) A resolver is allowed to cache answers, in your small test of zones it may
have done a series of iterative queries to find the answers, but once it had
the answers, future queries were answered from cache -- easy going and high
QPS, just limited by your memory/cpu performance.
2) When you added thousands of random sites it took it much longer to perform
all the look ups and begin storing cached results. A much more realistic test,
but slower going.
3) Not sure if you stopped/started named after each test? If you just left it
running, it still had many results cached and could use those in subsequent
tests.
4) UDP queue length - a realistic test would have several clients running
dnsperf and querying the same resolver. As the resolver falls behind, the UDP
queue of waiting requests grows and some of those are just dropped by the OS.
There's a lot going on under the hood!
Hope this helps!
John
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