[Pdns-users] PDNS Authoritative and Mariadb share single core but multiple available

[Otto Moerbeek]

On Thu, Oct 31, 2019 at 05:24:05PM +0200, George Asenov wrote:

> Yes I understand that this test is not relevant!
> 
> The one think I didn't understand is why two different services working with
> 2 different users share 1 core at 100% and not working on separate
> cores/treads ?
> Even if the requests are not overlapping i think the two services should
> work independently to each other or I'm mistaken somewhere?

The handling of client queries should use more cores. It's just the
master/slave processing that is single-threaded. As for two processes
sharing a core: I don't see the issue, the pattern is likely caused by
the master/slave processing being dependent on the DB, as Brian
suggested. Spreading the two over multiple cores will not make it
faster. And this is something the OS scheduler does and we have no
influence on.

	-Otto


> 
> On 31-Oct-19 17:16, Otto Moerbeek wrote:
> > On Thu, Oct 31, 2019 at 05:08:50PM +0200, George Asenov wrote:
> > 
> > > 
> > > Here is a dnsperf test
> > > https://monosnap.com/direct/IijS7l37a4r1Ck7dVKeO1UAf6kvEg0
> > > 
> > > # dnsperf -s XXX.XXX.XXX.XXX -c 10000 -T 5 -d domainslist.txt -n 100
> > > DNS Performance Testing Tool
> > > Nominum Version 2.1.0.0
> > > 
> > > [Status] Command line: dnsperf -s XXX.XXX.XXX.XXX -c 10000 -T 5 -d
> > > domainslist.txt -n 100
> > > [Status] Sending queries (to XXX.XXX.XXX.XXX)
> > > [Status] Started at: Thu Oct 31 07:43:52 2019
> > > [Status] Stopping after 100 runs through file
> > > [Status] Testing complete (end of file)
> > > 
> > > Statistics:
> > > 
> > >    Queries sent:         83800
> > >    Queries completed:    83800 (100.00%)
> > >    Queries lost:         0 (0.00%)
> > > 
> > >    Response codes:       NOERROR 24400 (29.12%), NXDOMAIN 1400 (1.67%),
> > > REFUSED 58000 (69.21%)
> > >    Average packet size:  request 36, response 43
> > >    Run time (s):         4.157266
> > >    Queries per second:   20157.478497
> > > 
> > >    Average Latency (s):  0.002703 (min 0.000924, max 0.265014)
> > >    Latency StdDev (s):   0.009624
> > > 
> > >   PDNS process all the requests sequentially not paralel?
> > > 
> > > If that is not a relevant test let me know how to.
> > 
> > We were talking about performance of notify etc. And now you're
> > posting something about general query performance.
> > 
> > I think your question about using a single core for master/slave
> > operations was answered. If you have more questions about that subject
> > say so.
> > 
> > If you want to talk about general performance (measurement) start a new
> > subject.
> > 
> > 	-Otto
> > 
> > > 
> > > On 31-Oct-19 16:37, Otto Moerbeek wrote:
> > > > On Thu, Oct 31, 2019 at 02:28:48PM +0000, Brian Candler wrote:
> > > > 
> > > > > On 31/10/2019 13:44, George Asenov wrote:
> > > > > > For example if the mariadb get 70% pdns 30% if i check the load by cores
> > > > > > one core has 0%id all other 3 are near 100%id .
> > > > > > here are some screenshots
> > > > > 
> > > > > Looks like sequential operation to me:
> > > > > 
> > > > > 1. pdns sends a query to mariadb (goes to sleep waiting for response)
> > > > > 
> > > > > 2. mariadb processes the query and sends back the response
> > > > > 
> > > > > 3. pdns processes the response, then sends the next query to mariadb
> > > > > 
> > > > > etc.
> > > > > 
> > > > > Without overlapping requests, pdns and mariadb will never be working at
> > > the
> > > > > same time.
> > > > > 
> > > > > _______________________________________________
> > > > > Pdns-users mailing list
> > > > > Pdns-users at mailman.powerdns.com
> > > > > https://mailman.powerdns.com/mailman/listinfo/pdns-users
> > > > 
> > > > Additionally, the master/slave work is done in a single thread. That
> > > > is generally good, since the other threads should be busy serving
> > > > requests. If you have a setup where there are little requests need to
> > > > be served, oh well, making the master/save operations multi-threaded
> > > > is probably not worth the added complexity.
> > > > 
> > > >      -Otto
> > > > 
> > > 
> > > -- 
> > > Warm regards
> > > George A.
> > > WPXHosting
> > > _______________________________________________
> > > Pdns-users mailing list
> > > Pdns-users at mailman.powerdns.com
> > > https://mailman.powerdns.com/mailman/listinfo/pdns-users
> > 
> 
> -- 
> Warm regards
> George A.
> WPXHosting
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