RE: [Bridge] Lowering CPU utilisation

[Brad Dameron <brad.dameron@clearwire.com>]

On Wed, 2007-11-07 at 08:51 +1100, Leigh Sharpe wrote:
> I'm using e1000 cards.
> According to oprofile, around 50% of the time is spent in the e1000
> driver. 
> Given that my load average is still under 0.5, I suspect I've got
> plenty of room for the driver to handle more traffic before I need to
> worry too much.
>  
> 
> 
> ______________________________________________________________________
> From: Vaidas M [mailto:admin@vdx.lt] 
> Sent: Tuesday, 6 November 2007 9:32 PM
> To: Leigh Sharpe
> Subject: RE: [Bridge] Lowering CPU utilisation
> 
> 
> 
> What kind of NIC you are using?
> 
> I suggest you to use cards with NAPI featured in driver.
> 
>  
> 
>                         _      _     _    _   _  _ _ __ ___ ____ _____
> 
>                                                             Vaidas M. 
> 
> 
>  
> 
> From: bridge-bounces@lists.linux-foundation.org
> [mailto:bridge-bounces@lists.linux-foundation.org] On Behalf Of Leigh
> Sharpe
> Sent: Thursday, November 01, 2007 12:00 AM
> To: bridge@lists.linux-foundation.org
> Subject: [Bridge] Lowering CPU utilisation
> 
> 
>  
> 
> Hi All, 
> 
> 
>  I have a box with 12 bridges on it, each of which has 2 ports.
> 
> 
> When the traffic level on the box reaches around 15-20Mbps on each
> bridge, my CPU utilisation gets to about 90-95%.
> 
> 
> I would like to avoid working the CPU that hard. Is there anything
> which can be done to get the CPU utlilisation down a bit? I have plans
> for an even bigger bridge, but these results indicate that it may not
> scale quite that well.
> 
> 
>  
> 
> 
> Regards,
>              Leigh
> 


I assume you are using Linux. Try setting these in your /etc/sysctl.conf
file.

# increase TCP max buffer size
net.core.rmem_max = 8388608
net.core.wmem_max = 8388608
# increase Linux autotuning TCP buffer limits
# min, default, and max number of bytes to use
net.ipv4.tcp_mem = 8388608 8388608 8388608
net.ipv4.tcp_rmem = 4096 1048576 8388608
net.ipv4.tcp_wmem = 4096 65535 8388608
net.core.optmem_max = 40960


Then load them with sysctl -p command.

Hope this helps. 


Brad Dameron
Senior Systems Engineer
Clearw're