[dnsdist] CPU Usage Dnsdist

[SAMI RAHAL]

Hello
exactly Frank when we decrease the number of rules the CPU usage decreases

Regards




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Envoyé : jeudi 25 mars 2021 13:00
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Objet : dnsdist Digest, Vol 67, Issue 9

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Today's Topics:

   1. CPU Usage Dnsdist (SAMI RAHAL)
   2. Re: CPU Usage Dnsdist (frank+pdns at tembo.be)


----------------------------------------------------------------------

Message: 1
Date: Wed, 24 Mar 2021 17:35:41 +0000
From: SAMI RAHAL <Sami.Rahal at topnetpro.tn>
To: "dnsdist at mailman.powerdns.com" <dnsdist at mailman.powerdns.com>
Subject: [dnsdist] CPU Usage Dnsdist
Message-ID: <cf645240fc3c46c7a77044ead9f027a8 at topnetpro.tn>
Content-Type: text/plain; charset="iso-8859-1"

Hello
I am monitoring dnsdist in production with a metronome server and also the native tool accessible through the default web server on port 8083, I got the following values:
Uptime: 2 hours, Number of queries: 86816060 (8060.00 qps), ACL drops: 0, Dynamic drops: 1639752, Rule drops: 4807
Average response time: 4.35 ms, CPU Usage: 750.60%, Cache hitrate: 93.45%, Server selection policy: leastOutstanding
I ask are these values in the norms?
my config:
OS: CentOS 7
-RAM 16 G
-grep -c ^ processor / proc / cpuinfo
16
-RAM used:
949 M
Is there a way to improve CPU usage value?


Regards
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Message: 2
Date: Wed, 24 Mar 2021 19:37:08 +0100
From: frank+pdns at tembo.be
To: SAMI RAHAL <Sami.Rahal at topnetpro.tn>
Cc: dnsdist mailing list <dnsdist at mailman.powerdns.com>
Subject: Re: [dnsdist] CPU Usage Dnsdist
Message-ID: <9452B0CD-AB99-44B5-ADFB-FB711E041107 at tembo.be>
Content-Type: text/plain; charset="us-ascii"

Hi,

> On 24 Mar 2021, at 18:35, SAMI RAHAL via dnsdist <dnsdist at mailman.powerdns.com <mailto:dnsdist at mailman.powerdns.com>> wrote:
>
> Average response time: 4.35 ms, CPU Usage: 750.60%, Cache hitrate: 93.45%, Server selection policy: leastOutstanding
> I ask are these values in the norms?
> my config:
> OS: CentOS 7
> -RAM 16 G
> -grep -c ^ processor / proc / cpuinfo
> 16
> -RAM used:
> 949 M

You would increase the cache size, as you're only using about 1GB of ram and have 16GB available. You also have 16 (v)cpus, but the CPU usage is under 800%. If I am not mistake, the CPU usage reported by dnsdist is "% of full utilisation of 1 cpu", so it should theoretically go up to 1600%.

If you do want to reduce the CPU usage, you might want to experiment with simplifying your lua rules and see if that improves or not.

Kind Regards,

Frank

Frank Louwers
PowerDNS Certified Consultant @ Kiwazo.be




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