Re: [lvs-users] sync daemon single CPU limits

To: Phillip Moore <pdm@xxxxxxxxx>
Subject: Re: [lvs-users] sync daemon single CPU limits
Cc: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
From: Julian Anastasov <ja@xxxxxx>
Date: Thu, 22 Aug 2019 21:39:42 +0300 (EEST)

On Thu, 22 Aug 2019, Phillip Moore wrote:

> Hello,
> I noticed that the ipvs-b process is tending towards 100% CPU utilization
> on some of my IPVS LB clusters. It seems process is limited to one core
> with our version of Centos7 (kernel 3.10.0-957). This would seem to put a
> practical limit on the number of sessions that can be handled even when
> network throughput is well below capacity. We've seen some recent increases
> in our connection counts and have started seeing some dropped packets on
> the VIPs.
> Has there been any changes in recent kernels to make this not be limited to
> a single core and to be able to handle a higher number of synced sessions?

        Yes, with sysctl var "sync_ports" by using same value on all
master and backup servers you can increase the number of ports
used which starts new thread for every port. There are other
vars that you can use to decrease the SYNC traffic, see my
answer here:

        Not sure if your kernel has all the options...

> Some context for the question. We have 8 linux servers in each cluster
> using keepalived to setup ip_vs. All nodes are active running both the
> master and backup sync processes (-a and -b). We use BGP to route traffic
> to the nodes.
> Thanks,
> Phillip


Julian Anastasov <ja@xxxxxx>

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