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Re: [lvs-users] ksoftirqd 100% Processor Usage

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] ksoftirqd 100% Processor Usage
From: Graeme Fowler <graeme@xxxxxxxxxxx>
Date: Mon, 24 Nov 2008 10:57:42 +0000
Hi

On Mon, 2008-11-24 at 19:39 +0900, Mikio Kishi wrote:
>  - NAT mode
>  - traffic generator is web clients
>    - sending HTTP GET requests
>  - traffic receiver is real server

OK...

> - (2) LVS host spec
> 
>  hardware: CPU: Xeon 2.33GHz  x  8(core)
>                                 ^^^^^^^^^

The number of cores in this case is not relevant.

> - (4) problem
> 
> When the CPS(new connections/sec) become over 15,000,
> %CPU of ksoftirqd "jump" to 100% !!!

What network card are you using on the director? There's only so many
interrupts you can generate from one NIC before the CPU wedges - and in
most cases every packet generates in interrupt. If you're using
plain-old-PCI, you get less throughput than more advanced PCI variants.

There was a thread about this recently. Search the archives for it.

Graeme



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