Re: [Patch V3 3/9] sgi-xp: Replace cpu_to_node() with cpu_to_mem() to support memoryless node
From: Robin Holt <robinmholt@gmail.com>
Date: 2015-08-19 11:53:03
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On Sun, Aug 16, 2015 at 10:19 PM, Jiang Liu [off-list ref] wrote:
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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 <redacted> --- 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>