From: Jose Luis Domingo Lopez <lartc@24x7linux.com>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] use or non-use of multiple processors in forwarding
Date: Sat, 09 Nov 2002 17:50:20 +0000 [thread overview]
Message-ID: <marc-lartc-103686430011190@msgid-missing> (raw)
In-Reply-To: <marc-lartc-103680424012201@msgid-missing>
On Friday, 08 November 2002, at 17:08:46 -0800,
Don Cohen wrote:
> I'm testing to see how fast A can ping C without losing packets.
> A -- B -- C
> B is a dual processor (Intel(R) XEON(TM) CPU 1.80GHz) machine.
>
> /proc/stat shows me that all of the work is done by one cpu, the other
> does nothing.
>
I am not sure of how networking works in Linux with respect to SMP, but
I do remember that kernels 2.4.x had as an important feature a
much-reworked SMP-aware network stack. In 2.2.x and older times, it
seems networking was approximately non SMP-aware (it was aware, but
inefficient).
2.4.x and beyond were reworked, and scaleability with number of CPUs is
much better than before. I remember having seen a benchmark at
www.linuxvirtualserver.org that detailled some test where it was clear
SMP support for networking in 2.4.x was much better than 2.2.x's.
Apart from that, maybe (I am not sure), due to CPU affinity, and as you
packets come from and go to the same addresses, the routing process is
bound to this CPU, without using the other.
Hope it helps (and hope the above is correct :-)
--
Jose Luis Domingo Lopez
Linux Registered User #189436 Debian Linux Woody (Linux 2.4.19-pre6aa1)
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next prev parent reply other threads:[~2002-11-09 17:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-11-09 1:08 [LARTC] use or non-use of multiple processors in forwarding Don Cohen
2002-11-09 17:50 ` Jose Luis Domingo Lopez [this message]
2002-11-11 21:13 ` Don Cohen
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