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Re: [Patch V3 3/9] sgi-xp: Replace cpu_to_node() with cpu_to_mem() to support memoryless node

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On Sun, Aug 16, 2015 at 10:19 PM, Jiang Liu <jiang.liu@linux.intel.com> wrote:
> Function xpc_create_gru_mq_uv() allocates memory with __GFP_THISNODE
> flag set, which may cause permanent memory allocation failure on
> memoryless node. So replace cpu_to_node() with cpu_to_mem() to better
> support memoryless node. For node with memory, cpu_to_mem() is the same
> as cpu_to_node().
>
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
> ---
>  drivers/misc/sgi-xp/xpc_uv.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/misc/sgi-xp/xpc_uv.c b/drivers/misc/sgi-xp/xpc_uv.c
> index 95c894482fdd..9210981c0d5b 100644
> --- a/drivers/misc/sgi-xp/xpc_uv.c
> +++ b/drivers/misc/sgi-xp/xpc_uv.c
> @@ -238,7 +238,7 @@ xpc_create_gru_mq_uv(unsigned int mq_size, int cpu, char *irq_name,
>
>         mq->mmr_blade = uv_cpu_to_blade_id(cpu);
>
> -       nid = cpu_to_node(cpu);
> +       nid = cpu_to_mem(cpu);

I would recommend rejecting this.  First, SGI's UV system does not and
can not support memory-less nodes.  Additionally the hardware _REALLY_
wants the memory to be local to the CPU.  We will register this memory
region with the node firmware.  That will set the hardware up to watch
this memory block and raise an IRQ targeting the registered CPU when
anything is written into the memory block.  This is all part of how
cross-partition communications expects to work.

Additionally, the interrupt handler will read the memory region, so
having node-local memory is extremely helpful.

Thanks,
Robin
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[Patch V3 0/9] Enable memoryless node support for x86 Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-17 05:20 +0200
  [Patch V3 6/9] i40evf: Use numa_mem_id() to better support memoryless node Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-17 05:20 +0200
    RE: [Intel-wired-lan] [Patch V3 6/9] i40evf: Use numa_mem_id() to  better support memoryless node "Patil, Kiran" <kiran.patil@intel.com> - 2015-08-17 21:10 +0200
      Re: [Intel-wired-lan] [Patch V3 6/9] i40evf: Use numa_mem_id() to  better support memoryless node Jeff Kirsher <jeffrey.t.kirsher@intel.com> - 2015-08-18 23:40 +0200
  [Patch V3 9/9] mm, x86: Enable memoryless node support to better support CPU/memory hotplug Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-17 05:20 +0200
    Re: [Patch V3 9/9] mm, x86: Enable memoryless node support to better  support CPU/memory hotplug Tang Chen <tangchen@cn.fujitsu.com> - 2015-08-18 08:20 +0200
      Re: [Patch V3 9/9] mm, x86: Enable memoryless node support to better  support CPU/memory hotplug Tang Chen <tangchen@cn.fujitsu.com> - 2015-08-18 13:40 +0200
    Re: [Patch V3 9/9] mm, x86: Enable memoryless node support to better  support CPU/memory hotplug Ingo Molnar <mingo@kernel.org> - 2015-08-18 09:40 +0200
  [Patch V3 1/9] x86, NUMA, ACPI: Online node earlier when doing CPU hot-addition Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-17 05:20 +0200
  [Patch V3 2/9] kernel/profile.c: Replace cpu_to_mem() with cpu_to_node() Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-17 05:20 +0200
    Re: [Patch V3 2/9] kernel/profile.c: Replace cpu_to_mem() with  cpu_to_node() David Rientjes <rientjes@google.com> - 2015-08-18 02:40 +0200
      Re: [Patch V3 2/9] kernel/profile.c: Replace cpu_to_mem() with  cpu_to_node() Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-19 09:20 +0200
        Re: [Patch V3 2/9] kernel/profile.c: Replace cpu_to_mem() with  cpu_to_node() David Rientjes <rientjes@google.com> - 2015-08-20 02:10 +0200
  [Patch V3 4/9] openvswitch: Replace cpu_to_node() with cpu_to_mem() to support memoryless node Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-17 05:20 +0200
    Re: [Patch V3 4/9] openvswitch: Replace cpu_to_node() with  cpu_to_mem() to support memoryless node Pravin Shelar <pshelar@nicira.com> - 2015-08-18 02:20 +0200
  [Patch V3 7/9] x86, numa: Kill useless code to improve code readability Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-17 05:20 +0200
  [Patch V3 3/9] sgi-xp: Replace cpu_to_node() with cpu_to_mem() to support memoryless node Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-17 05:20 +0200
    Re: [Patch V3 3/9] sgi-xp: Replace cpu_to_node() with cpu_to_mem()  to support memoryless node David Rientjes <rientjes@google.com> - 2015-08-18 02:30 +0200
      Re: [Patch V3 3/9] sgi-xp: Replace cpu_to_node() with cpu_to_mem() to  support memoryless node Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-19 10:30 +0200
        Re: [Patch V3 3/9] sgi-xp: Replace cpu_to_node() with cpu_to_mem()  to support memoryless node David Rientjes <rientjes@google.com> - 2015-08-20 02:10 +0200
          Re: [Patch V3 3/9] sgi-xp: Replace cpu_to_node() with cpu_to_mem() to  support memoryless node Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-20 08:40 +0200
    Re: [Patch V3 3/9] sgi-xp: Replace cpu_to_node() with cpu_to_mem() to  support memoryless node Robin Holt <robinmholt@gmail.com> - 2015-08-19 14:00 +0200
      Re: [Patch V3 3/9] sgi-xp: Replace cpu_to_node() with cpu_to_mem() to  support memoryless node Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-19 14:50 +0200
  [Patch V3 5/9] i40e: Use numa_mem_id() to better support memoryless node Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-17 05:20 +0200
    Re: [Patch V3 5/9] i40e: Use numa_mem_id() to better support memoryless  node David Rientjes <rientjes@google.com> - 2015-08-18 02:40 +0200
    RE: [Intel-wired-lan] [Patch V3 5/9] i40e: Use numa_mem_id() to  better support memoryless node "Patil, Kiran" <kiran.patil@intel.com> - 2015-08-20 00:40 +0200
      RE: [Intel-wired-lan] [Patch V3 5/9] i40e: Use numa_mem_id() to  better support memoryless node David Rientjes <rientjes@google.com> - 2015-08-20 02:20 +0200
  [Patch V3 8/9] mm: Update _mem_id_[] for every possible CPU when memory configuration changes Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-17 05:20 +0200
  Re: [Patch V3 0/9] Enable memoryless node support for x86 Andrew Morton <akpm@linux-foundation.org> - 2015-08-17 23:40 +0200
  Re: [Patch V3 0/9] Enable memoryless node support for x86 Tang Chen <tangchen@cn.fujitsu.com> - 2015-08-18 12:10 +0200
    Re: [Patch V3 0/9] Enable memoryless node support for x86 Jiang Liu <jiang.liu@linux.intel.com> - 2015-08-19 10:10 +0200

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