Messages in this thread | | | Date | Fri, 17 Aug 2012 14:09:21 +0000 | From | Christoph Lameter <> | Subject | Re: [PATCH V2] mm: introduce N_LRU_MEMORY to distinguish between normal and movable memory |
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On Fri, 17 Aug 2012, Hanjun Guo wrote:
> N_NORMAL_MEMORY means non-LRU page allocs possible.
Hmmm... It may be better to say
N_NORMAL_MEMORY Allocations are allowed for pages that will not be managed via a LRU and that cannot be moved by the page migration logic.
N_LRU_MEMORY Allocations are possible for pages that are managed via LRUs
N_HIGH_MEMORY Allocations are allowed for pages that are only temporarliy mapped into kernel address space.
Any node that has the ability to allocate memory at all has at least N_LRU_MEMORY set.
> > /* > * Bitmasks that are kept for all the nodes. > + * N_NORMAL_MEMORY means non-LRU page allocs possible. > + * N_LRU_MEMORY means LRU page allocs possible, > + * node with ZONE_DMA/ZONE_DMA32/ZONE_NORMAL is marked with > + * N_LRU_MEMORY and N_NORMAL_MEMORY, > + * node with ZONE_MOVABLE is *only* marked with N_LRU_MEMORY, > + * node with ZONE_HIGHMEM is marked with N_LRU_MEMORY and N_HIGH_MEMORY. > + * N_LRU_MEMORY also means node has any regular memory. > */ > enum node_states { > N_POSSIBLE, /* The node could become online at some point */ > N_ONLINE, /* The node is online */ > - N_NORMAL_MEMORY, /* The node has regular memory */ > + N_NORMAL_MEMORY, /* The node has normal memory */ > + N_LRU_MEMORY, /* The node has regular memory */
These comments are utter garbage and just repeat what the constant alreadty expresses. . Please actually say something meaningful that another developer can use when he attempts to understand what these bits mean.
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