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Re: How to map NIC to cpu socket?

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On Sunday 07 September 2014 02:32, David W. Hodgins conveyed the 
following to comp.os.linux.misc...

> On Sat, 06 Sep 2014 18:52:00 -0400, Wayne <nospam@all.invalid> wrote:
> 
>> Info about NUMA:
>> <https://software.intel.com/en-us/articles/optimizing-applications-
for-numa?wapkw=optimizing%20software%20applications%20for%20numa>
> 
> Thanks for that link. I was not aware of numa, and don't have it on
> any of the systems I have access to, hence my earlier comment about
> the nic being accessed over the pci bus, by any cpu.
> 
> The op's question does make sense now, assuming the system in use does
> support numa.

I own a NUMA machine - not in use at the moment - based upon a Tyan 
motherboard and second generation AMD Opteron processors, and it has two 
NICs, on on each node [*].  

As I understand it, the kernel will handle the NUMA layout based upon 
the information it receives from the BIOS.  Linux has already had 
excellent NUMA support for a very long time.  If I'm not mistaken, then 
that was already implemented somewhere early on during the lifetime of 
the 2.6 kernel generation.  

If one builds one's own kernels from sources, then one can choose 
whether NUMA should be used or whether a flat memory model is desirable, 
but distro kernels are typically compiled with NUMA support, in which 
case Linux will detect whether the system really /is/ a NUMA 
architecture - this also depends on BIOS settings, as the BIOS can 
disable the NUMA layout and implement plain SMP instead - and if the 
system isn't configured for NUMA, then Linux will simply treat the whole 
memory layout and processor architecture as being a single NUMA node, 
which works just as well as the flat memory model.  Performance might be 
marginally less than optimal with this approach, but the difference will 
be smaller than that of the performance penalty associated with using 
generic "lowest common denominator" x86(-64) code rather than processor 
brand- and processor type-specific register optimizations.


[*] It's a bit ironic that such an article should appear on Intel's
    website, given that AMD has been implementing all their own AMD64
    processors as NUMA from the start, while Intel waited with
    implementing NUMA on x86-64 until the Core i series and kept on
    implementing all their multisocket x86-64 processors as plain old
    SMP platforms up until and including the Core 2 series.  (Intel
    did already have experience at building NUMA boards, but they were
    very rare in the x86 market.)

-- 
= Aragorn =

         http://www.linuxcounter.net - registrant #223157

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How to map NIC to cpu socket? chrippa08@gmail.com - 2014-09-05 06:01 -0700
  Re: How to map NIC to cpu socket? Joe Beanfish <joebeanfish@nospam.duh> - 2014-09-05 13:09 +0000
    Re: How to map NIC to cpu socket? Robert Heller <heller@deepsoft.com> - 2014-09-05 08:51 -0500
      Re: How to map NIC to cpu socket? chrippa08@gmail.com - 2014-09-05 07:49 -0700
        Re: How to map NIC to cpu socket? Robert Heller <heller@deepsoft.com> - 2014-09-05 11:15 -0500
        Re: How to map NIC to cpu socket? "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2014-09-05 12:15 -0400
        Re: How to map NIC to cpu socket? William Unruh <unruh@invalid.ca> - 2014-09-05 20:48 +0000
          Re: How to map NIC to cpu socket? chrippa08@gmail.com - 2014-09-05 23:34 -0700
            Re: How to map NIC to cpu socket? Wayne <nospam@all.invalid> - 2014-09-06 18:52 -0400
              Re: How to map NIC to cpu socket? "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2014-09-06 20:32 -0400
                Re: How to map NIC to cpu socket? Aragorn <thorongil@telenet.be.invalid> - 2014-09-07 14:19 +0200
                Re: How to map NIC to cpu socket? Wayne <nospam@all.invalid> - 2014-09-08 04:41 -0400
                Re: How to map NIC to cpu socket? Aragorn <thorongil@telenet.be.invalid> - 2014-09-08 14:07 +0200
              Re: How to map NIC to cpu socket? chrippa08@gmail.com - 2014-09-08 03:05 -0700

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