Bind 9.10.3 on CentOS 7.1 - Recv-q on vmware

Mukund Sivaraman muks at
Wed Dec 16 08:21:29 UTC 2015

Hi Rasmus

On Tue, Dec 15, 2015 at 03:20:05PM +0100, Rasmus Edgar wrote:
> We started noticing 1s+ latency problems on clients resolving using the
> vmware guest at a load around 6000 qps.
> Test setup:
> 1 x x86_64 vmware guest on Esx 5.5
> 8xVCPU
> 8G RAM
> vmxnet3 10Gb virtual interface
> CentOS 7.1
> Bind 9.10.3 resolver
> 1xIBM x86_64 physical machine
> 24xCPU cores
> 16G ram
> 1Gb interface
> CentOS 7.1
> Bind 9.10.3 resolver

Generally VMs are not a proper place to test query performance, but
anyway let's see.  When named starts, it logs messages like this:

15-Dec-2015 20:08:00.245 found 8 CPUs, using 8 worker threads
15-Dec-2015 20:08:00.245 using 7 UDP listeners per interface
15-Dec-2015 20:08:00.245 using up to 4096 sockets

Please will you paste what you get in your configuration?

> ./dnsperf -f inet -s <redacted ip> -d queryfile-example-10million-201202 -l
> 30 -q 15000

Why are you passing the -q argument to dnsperf?

A high receive queue means your named process is not able to read off
the socket fast enough. Try to find out where it's busy, using a
profiler such as perf. Is it query logging or doing some other highly
verbose logging that keeps it blocked in disk IO?

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