Messages in this thread | | | Date | Fri, 30 May 2014 08:48:41 -0500 (CDT) | From | Christoph Lameter <> | Subject | Re: [PATCH] page_alloc: skip cpuset enforcement for lower zone allocations (v4) |
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On Thu, 29 May 2014, Andrew Morton wrote:
> > > > if (!nodemask && gfp_zone(gfp_mask) < policy_zone) > > nodemask = &node_states[N_ONLINE]; > > OK, thanks, I made the patch go away for now. >
And another issue is that the policy_zone may be highmem on 32 bit platforms which will result in ZONE_NORMAL to be exempted.
policy zone can actually even be ZONE_DMA for some platforms. The check would not be useful at all on those.
Ignoring the containing cpuset only makes sense for GFP_DMA32 on 64 bit platforms and for GFP_DMA on platforms where there is an actual difference in the address spaces supported by GFP_DMA (such as x86).
Generally I think this is only useful for platforms that attempt to support legacy devices only able to DMA to a portion of the memory address space and that at the same time support NUMA for large address spaces. This is a contradiction on the one hand this is a high end system and on the other hand it attempts to support crippled DMA devices?
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