Christoph Lameter a écrit :
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.
Hum, maybe, but then we broke modules that might request up to PAGE_SIZE
alignement for their percpu section,
if I read your 3rd patch correctly.
Taking into account the ((unsigned long)area & (PAGE_SIZE-1)) offset in
cpu_alloc()
should give up to PAGE_SIZE alignment for free.
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