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*参照元 [#def80dce] #backlinks *説明 [#a9fb42d9] -パス: [[linux-4.4.1/include/linux/gfp.h]] -FIXME: これは何？ --説明 **参考 [#bd1c02c4] *実装 [#c0da103b] /* * Useful GFP flag combinations that are commonly used. It is recommended * that subsystems start with one of these combinations and then set/clear * __GFP_FOO flags as necessary. * * GFP_ATOMIC users can not sleep and need the allocation to succeed. A lower * watermark is applied to allow access to "atomic reserves" * * GFP_KERNEL is typical for kernel-internal allocations. The caller requires * ZONE_NORMAL or a lower zone for direct access but can direct reclaim. * * GFP_NOWAIT is for kernel allocations that should not stall for direct * reclaim, start physical IO or use any filesystem callback. * * GFP_NOIO will use direct reclaim to discard clean pages or slab pages * that do not require the starting of any physical IO. * * GFP_NOFS will use direct reclaim but will not use any filesystem interfaces. * * GFP_USER is for userspace allocations that also need to be directly * accessibly by the kernel or hardware. It is typically used by hardware * for buffers that are mapped to userspace (e.g. graphics) that hardware * still must DMA to. cpuset limits are enforced for these allocations. * * GFP_DMA exists for historical reasons and should be avoided where possible. * The flags indicates that the caller requires that the lowest zone be * used (ZONE_DMA or 16M on x86-64). Ideally, this would be removed but * it would require careful auditing as some users really require it and * others use the flag to avoid lowmem reserves in ZONE_DMA and treat the * lowest zone as a type of emergency reserve. * * GFP_DMA32 is similar to GFP_DMA except that the caller requires a 32-bit * address. * * GFP_HIGHUSER is for userspace allocations that may be mapped to userspace, * do not need to be directly accessible by the kernel but that cannot * move once in use. An example may be a hardware allocation that maps * data directly into userspace but has no addressing limitations. * * GFP_HIGHUSER_MOVABLE is for userspace allocations that the kernel does not * need direct access to but can use kmap() when access is required. They * are expected to be movable via page reclaim or page migration. Typically, * pages on the LRU would also be allocated with GFP_HIGHUSER_MOVABLE. * * GFP_TRANSHUGE is used for THP allocations. They are compound allocations * that will fail quickly if memory is not available and will not wake * kswapd on failure. */ #define GFP_ATOMIC (__GFP_HIGH|__GFP_ATOMIC|__GFP_KSWAPD_RECLAIM) #define GFP_KERNEL (__GFP_RECLAIM | __GFP_IO | __GFP_FS) #define GFP_NOWAIT (__GFP_KSWAPD_RECLAIM) #define GFP_NOIO (__GFP_RECLAIM) #define GFP_NOFS (__GFP_RECLAIM | __GFP_IO) #define GFP_TEMPORARY (__GFP_RECLAIM | __GFP_IO | __GFP_FS | \ __GFP_RECLAIMABLE) #define GFP_USER (__GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL) #define GFP_DMA __GFP_DMA #define GFP_DMA32 __GFP_DMA32 #define GFP_HIGHUSER (GFP_USER | __GFP_HIGHMEM) #define GFP_HIGHUSER_MOVABLE (GFP_HIGHUSER | __GFP_MOVABLE) #define GFP_TRANSHUGE ((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \ __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN) & \ ~__GFP_KSWAPD_RECLAIM) - --[[linux-4.4.1/__GFP_KSWAPD_RECLAIM]] *コメント [#j03bdd48]
