[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    [W:0.020 / U:31.672 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site