Stuart,
You didn't mention what OS you are using, I assume some version of
Linux. What you are seeing may not be a BIND limit, but the OS. One thing we
noted with Redhat is that the kernel just couldn't keep up with the inbound UDP
packets (queue overflow). The kernel does keep a count of dropped UDP
packets; unfortunately, I can't recall the command we used to monitor. Found
this on Google,
https://linux-tips.com/t/udp-packet-drops-and-packet-receive-error-difference/237
.
Perhaps the other folks have better details.
Best regards!
John
------------------------------
Message: 4
Date: Wed, 31 May 2017 07:25:44 +0000
From: "Browne, Stuart" <[email protected]>
To: "[email protected]" <[email protected]>
Subject: Tuning suggestions for high-core-count Linux servers
Message-ID:
<07ef8b18a5248a4691e86a8e16bdbd87013bd...@stntexmb11.cis.neustar.com>
Content-Type: text/plain; charset="us-ascii"
Hi,
I've been able to get my hands on some rather nice servers with 2 x 12 core
Intel CPU's and was wondering if anybody had any decent tuning tips to get BIND
to respond at a faster rate.
I'm seeing that pretty much cpu count beyond a single die doesn't get any real
improvement. I understand the NUMA boundaries etc., but this hasn't been my
experience on previous iterations of the Intel CPU's, at least not this
dramatically. When I use more than a single die, CPU utilization continues to
match the core count however throughput doesn't increase to match.
All the testing I've been doing for now (dnsperf from multiple sources for now)
seems to be plateauing around 340k qps per BIND host.
Some notes:
- Primarily looking at UDP throughput here
- Intention is for high-throughput, authoritative only
- The zone files used for testing are fairly small and reside completely
in-memory; no disk IO involved
- RHEL7, bind 9.10 series, iptables 'NOTRACK' firmly in place
- Current configure:
built by make with '--build=x86_64-redhat-linux-gnu'
'--host=x86_64-redhat-linux-gnu' '--program-prefix='
'--disable-dependency-tracking' '--prefix=/usr' '--exec-prefix=/usr'
'--bindir=/usr/bin' '--sbindir=/usr/sbin' '--sysconfdir=/etc'
'--datadir=/usr/share' '--includedir=/usr/include' '--libdir=/usr/lib64'
'--libexecdir=/usr/libexec' '--sharedstatedir=/var/lib'
'--mandir=/usr/share/man' '--infodir=/usr/share/info' '--localstatedir=/var'
'--with-libtool' '--enable-threads' '--enable-ipv6' '--with-pic'
'--enable-shared' '--disable-static' '--disable-openssl-version-check'
'--with-tuning=large' '--with-libxml2' '--with-libjson'
'build_alias=x86_64-redhat-linux-gnu' 'host_alias=x86_64-redhat-linux-gnu'
'CFLAGS= -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions
-fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64
-mtune=generic -fPIC' 'LDFLAGS=-Wl,-z,relro ' 'CPPFLAGS= -DDIG_SIGCHASE -fPIC'
Things tried:
- Using 'taskset' to bind to a single CPU die and limiting BIND to '-n' cpu's
doesn't improve much beyond letting BIND make its own decision
- NIC interfaces are set for TOE
- rmem & wmem changes (beyond a point) seem to do little to improve
performance, mainly just make throughput more consistent
I've yet to investigate the switch throughput or tweaking (don't yet have
access to it).
So, any thoughts?
Stuart
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