[lkml]   [2008]   [May]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [patch 02/41] cpu alloc: The allocator
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
should give up to PAGE_SIZE alignment for free.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2008-05-30 07:57    [from the cache]
©2003-2014 Jasper Spaans. hosted at Digital Ocean