Re: [PATCH 00/07][RFC] i386: NUMA emulation

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Mon, 3 Oct 2005, Magnus Damm wrote:

Date: Mon, 3 Oct 2005 19:02:08 +0900
From: Magnus Damm <[email protected]>
To: David Lang <[email protected]>
Cc: Dave Hansen <[email protected]>, Magnus Damm <[email protected]>,
    linux-mm <[email protected]>,
    Linux Kernel Mailing List <[email protected]>
Subject: Re: [PATCH 00/07][RFC] i386: NUMA emulation

On 10/3/05, David Lang <[email protected]> wrote:
On Mon, 3 Oct 2005, Magnus Damm wrote:

On 10/1/05, Dave Hansen <[email protected]> wrote:
On Fri, 2005-09-30 at 16:33 +0900, Magnus Damm wrote:
These patches implement NUMA memory node emulation for regular i386 PC:s.

NUMA emulation could be used to provide coarse-grained memory resource control
using CPUSETS. Another use is as a test environment for NUMA memory code or
CPUSETS using an i386 emulator such as QEMU.

This patch set basically allows the "NUMA depends on SMP" dependency to
be removed.  I'm not sure this is the right approach.  There will likely
never be a real-world NUMA system without SMP.  So, this set would seem
to include some increased (#ifdef) complexity for supporting SMP && !
NUMA, which will likely never happen in the real world.

Yes, this patch set removes "NUMA depends on SMP". It also adds some
simple NUMA emulation code too, but I am sure you are aware of that!
=)

I agree that it is very unlikely to find a single-processor NUMA
system in the real world. So yes, "[PATCH 02/07] i386: numa on
non-smp" adds _some_ extra complexity. But because SMP is set when
supporting more than one cpu, and NUMA is set when supporting more
than one memory node, I see no reason why they should be dependent on
each other. Except that they depend on each other today and breaking
them loose will increase complexity a bit.

hmm, observation from the peanut gallery, would it make sene to look at
useing the NUMA code on single proc machines that use PAE to access more
then 4G or ram on a 32 bit system?

Hm, maybe? =) What would you like to accomplish by that?

if nothing else preferential use of 'local' (non PAE) memory over 'remote' (PAE) memory for programs, while still useing it all as needed.

this may be done already, but this type of difference between the access speed of different chunks of ram seems to be exactly the type of thing that the NUMA code solves the general case for. I'm thinking that it may end up simplifying things if the same general-purpose logic will work for the specific case of PAE instead of it being hard coded as a special case.

it also just struck me as the most obvious example of where a UP box could have a NUMA-like memory arrangement (and therefor a case to justify decoupling the SMP and NUMA options)

David Lang

/ magnus


--
There are two ways of constructing a software design. One way is to make it so simple that there are obviously no deficiencies. And the other way is to make it so complicated that there are no obvious deficiencies.
 -- C.A.R. Hoare
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux