Unexpected srrt in loopback

[Darcy Kevin (FCA)]

The network transit time over software loopback should be minimal, but network transit time isn't the only thing which contributes to overall RTT.

Sounds like your named process is struggling to keep up with 5000 QPS. Have you looked at the memory, CPU? Are you running with a single thread, or multiple threads? Are you bumping into operating-system limits (which are, depending on platform, tunable in named.conf)? There could be a lot of reasons why named gets backed up in processing requests, and these aren't necessarily evident from doing a simple dig against an otherwise-idle named instance.

                                                                                                                                - Kevin

From: bind-users-bounces at lists.isc.org [mailto:bind-users-bounces at lists.isc.org] On Behalf Of ???
Sent: Tuesday, November 04, 2014 4:39 AM
To: bind-users at lists.isc.org
Subject: Unexpected srrt in loopback


Hi everyone, I try to set up an authentic bind server in the loopback address(127.0.0.1) in our recursive server of our testbed for test reason. When I send a large number of junk queries(5000QPS), the srrt of loopback server in cash is unexpectedly large. Does anyone know the reason? The srrt is normal when I dig or ping the loopback server by the way.

The dump_cache.db's content:

; Address database dump

;

; 10.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::13 [srtt 212] [flags 00002000] [ttl 1746]

; 8.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::11 [srtt 744] [flags 00002000] [ttl 1746]

; 3.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::6 [srtt 171] [flags 00002000] [ttl 1746]

; 9.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::12 [srtt 44] [flags 00002000] [ttl 1746]

; 4.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::7 [srtt 64] [flags 00002000] [ttl 1746]

; 13.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::16 [srtt 26] [flags 00002000] [ttl 1746]

; 5.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::8 [srtt 29] [flags 00002000] [ttl 1746]

; 12.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::15 [srtt 2054] [flags 00002000] [ttl 1746]

; 6.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::9 [srtt 663] [flags 00002000] [ttl 1746]

; 1.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::2 [srtt 550] [flags 00002000] [ttl 1746]

; 11.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::14 [srtt 44] [flags 00002000] [ttl 1746]

; 7.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::10 [srtt 918] [flags 00002000] [ttl 1746]

; 2.root-servers.net [v4 TTL 10744] [v6 TTL 86344] [v4 nxrrset] [v6 success]

;       240c:f:1:122::5 [srtt 360] [flags 00002000] [ttl 1746]

; Unassociated entries

;

;       ::1 [srtt 689] [flags 00002000] [ttl 1745]







Best Regards

Runxia Wan

---------------
Runxia Wan(Brian)

Research Engineer
BII Lab

Beijing Internet Institute(BII)

rxwan at biigroup.cn<mailto:rxwan at biigroup.cn>
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