Messages in this thread | | | Date | Thu, 8 Sep 2005 10:40:39 +0900 | From | Magnus Damm <> | Subject | Re: [PATCH] i386: single node SPARSEMEM fix |
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On 9/8/05, Dave Hansen <haveblue@us.ibm.com> wrote: > On Tue, 2005-09-06 at 12:56 +0900, Magnus Damm wrote: > > This patch for 2.6.13-git5 fixes single node sparsemem support. In the case > > when multiple nodes are used, setup_memory() in arch/i386/mm/discontig.c calls > > get_memcfg_numa() which calls memory_present(). The single node case with > > setup_memory() in arch/i386/kernel/setup.c does not call memory_present() > > without this patch, which breaks single node support. > > First of all, this is really a feature addition, not a bug fix. :)
From the POV that you can use sparsemem on a PC, yes. But from the POV that setup_memory() in arch/i386/kernel/setup.c not includes a call to memory_present(), I think it is a fix. =)
While at it, why do we have two copies of setup_memory()? Couldn't NUMA and non-NUMA share the same code? OTOH, NUMA and discontigmem seems very integrated/mixed up and there seems to be much activity in this field so maybe it is nice to keep the NUMA part separated anyway.
> The reason we haven't included this so far is that we don't really have > any machines that need sparsemem on i386 that aren't NUMA. So, we > disabled it for now, and probably need to decide first why we need it > before a patch like that goes in.
Well, I do not have any hardware here that requires sparsemem either, but I wanted to add NUMA emulation code to be able to run some multiple-memory-nodes tests on a virtual PC in QEMU. And this little patch shows my first step which involved getting sparsememto run on a PC.
> I actually have exactly the same patch that you sent out in my tree, but > it's just for testing. Magnus, perhaps we can get some of my testing > patches in good enough shape to put them in -mm so that the non-NUMA > folks can do more sparsemem testing.
Well, my NUMA emulation project has been postponed a bit now, but sooner or later I or someone else will need sparsemem on non-NUMA. So getting your testing patches in to -mm seems like a good idea!
Thanks!
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