Re: Single core gets pegged on multi-core PPTP server

Hi,
try with more recent version of accel-ppp (1.5 is lastest) and newer
kernel - there
are several critical bugs in older kernels


P.S the project accel-pptp has changed its name to accel-ppp

cheers

On Fri, Jan 20, 2012 at 12:35 AM, Bradley Peterson [off-list ref] wrote:

Hello,

I am trying to test the capacity of a linux PPTP server, both in
number of connections, and in packets per second.  I am using kernel
2.6.38.8, with the ppp, pptp, and gre modules, and accel-pptp 0.8.3.
I have RPS, RFS, and XPS enabled on the network devices for SMP
support.

But I'm seeing one CPU get pegged out with soft interrupt, while the
others are almost completely idle.

In my current test, I'm starting 250 pptp connections from another
server, then running iperf across each connection.  The client machine
pegs out, sure, but I'm surprised the server pegs out a single CPU.
With RPS, I would expect softirq's to be more balanced.

Where could the bottleneck be?  Do all ppp packets need to be
processed serially?

Brad
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