Messages in this thread | | | Date | Wed, 04 Jun 2008 07:58:12 -0700 | From | Mike Travis <> | Subject | Re: [patch 02/41] cpu alloc: The allocator |
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Christoph Lameter wrote: > On Fri, 30 May 2008, Eric Dumazet wrote: > >>> +static DEFINE_PER_CPU(UNIT_TYPE, area[UNITS]); >>> >> area[] is not guaranteed to be aligned on anything but 4 bytes. >> >> If someone then needs to call cpu_alloc(8, GFP_KERNEL, 8), it might get an non >> aligned result. >> >> Either you should add an __attribute__((__aligned__(PAGE_SIZE))), >> or take into account the real address of area[] in cpu_alloc() to avoid waste >> of up to PAGE_SIZE bytes >> per cpu. > > I think cacheline aligning should be sufficient. People should not > allocate large page aligned objects here.
I'm a bit confused. Why is DEFINE_PER_CPU_SHARED_ALIGNED() conditioned on ifdef MODULE?
#ifdef MODULE #define SHARED_ALIGNED_SECTION ".data.percpu" #else #define SHARED_ALIGNED_SECTION ".data.percpu.shared_aligned" #endif
#define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \ __attribute__((__section__(SHARED_ALIGNED_SECTION))) \ PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name \ ____cacheline_aligned_in_smp
Thanks, Mike
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