[Dnsmasq-discuss] Maximum concurrent tcp dns requests with dnsmasq

[Simon Kelley]

change MAX_PROCS in src/config.h and recompile.

Simon.

On 02/12/2022 14:15, Jan Horstmann via Dnsmasq-discuss wrote:
> Hi,
> it seems that dnsmasq with mostly default parameters can be easily
> overwhelmed with tcp dns requests. Even for 64 nearly concurrent
> requests some will take longer than a second to be answered [1]. This
> gets worse with the number of requests.
> Are there any tunables which could improve this?
> 
> Regards
> Jan
> 
> 
> [1]
> root at 8cb67b32dabb:/# dnsmasq --version
> Dnsmasq version 2.86  Copyright (c) 2000-2021 Simon Kelley
> Compile time options: IPv6 GNU-getopt DBus no-UBus i18n IDN2 DHCP
> DHCPv6 no-Lua TFTP conntrack ipset auth cryptohash DNSSEC loop-detect
> inotify dumpfile
> [...]
> root at 8cb67b32dabb:/# dnsmasq --no-hosts --no-resolv --local-service --
> bind-dynamic --server=1.1.1.1
> root at 8cb67b32dabb:/# time dig +short +tcp thekelleys.org.uk @127.0.0.1
> 85.119.82.65
> 
> real	0m0.076s
> user	0m0.019s
> sys	0m0.016s
> root at 8cb67b32dabb:/# for i in {0..63}; do time dig +short +tcp
> thekelleys.org.uk @127.0.0.1 & done | grep -c '85.119.82.65'
> 
> real	0m0.064s
> user	0m0.012s
> sys	0m0.010s
> 
> real	0m0.074s
> user	0m0.009s
> sys	0m0.011s
> 
> [...]
> 
> real	0m0.359s
> user	0m0.014s
> sys	0m0.004s
> 
> real	0m1.190s
> user	0m0.009s
> sys	0m0.012s
> 
> real	0m1.171s
> user	0m0.012s
> sys	0m0.007s
> 
> real	0m1.192s
> user	0m0.009s
> sys	0m0.011s
> 64
> 
>