> On Tue, 2 Oct 2007 00:43:24 -0700 > Andrew Morton <[EMAIL PROTECTED]> wrote: > > > On Tue, 2 Oct 2007 16:36:24 +0900 KAMEZAWA Hiroyuki <[EMAIL PROTECTED]> > > > > Don't think so. A node is a lump of circuitry which can have zero or > > > > more > > > > CPUs, IO and memory. > > > > > > > > It may initially have been conceived as a memory-only concept in the > > > > Linux > > > > kernel, but that doesn't fully map onto reality (does it?) > > > > > > > > There was a real-world need for this, I think from the Fujitsu guys. > > > > That > > > > should be spelled out in the changelog but isn't. > > > > > > Yes, Fujitsu and HP guys really need this memory-less-node support. > > > > > > > For what reason, please? > > > > For fujitsu, problem is called "empty" node. > > When ACPI's SRAT table includes "possible nodes", ia64 > bootstrap(acpi_numa_init) > creates nodes, which includes no memory, no cpu. > > I tried to remove empty-node in past, but that was denied. > It was because we can hot-add cpu to the empty node. > (node-hotplug triggered by cpu is not implemented now. and it will be ugly.) > > > For HP, (Lee can comment on this later), they have memory-less-node. > As far as I hear, HP's machine can have following configration. > > (example) > Node0: CPU0 memory AAA MB > Node1: CPU1 memory AAA MB > Node2: CPU2 memory AAA MB > Node3: CPU3 memory AAA MB > Node4: Memory XXX GB > > AAA is very small value (below 16MB) and will be omitted by ia64 bootstrap. > After boot, only Node 4 has valid memory (but have no cpu.) > > Maybe this is memory-interleave by firmware config.
>From memory-hotplug view, memory-less node is very helpful. It can define and arrange some "halfway conditions" of node hot-plug. I guess that node unpluging code will be simpler by it. Bye. -- Yasunori Goto - 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/
