• Mark Fasheh's avatar
    ocfs2: throttle back local alloc when low on disk space · 9c7af40b
    Mark Fasheh authored
    Ocfs2's local allocator disables itself for the duration of a mount point
    when it has trouble allocating a large enough area from the primary bitmap.
    That can cause performance problems, especially for disks which were only
    temporarily full or fragmented. This patch allows for the allocator to
    shrink it's window first, before being disabled. Later, it can also be
    re-enabled so that any performance drop is minimized.
    To do this, we allow the value of osb->local_alloc_bits to be shrunk when
    needed. The default value is recorded in a mostly read-only variable so that
    we can re-initialize when required.
    Locking had to be updated so that we could protect changes to
    local_alloc_bits. Mostly this involves protecting various local alloc values
    with the osb spinlock. A new state is also added, OCFS2_LA_THROTTLED, which
    is used when the local allocator is has shrunk, but is not disabled. If the
    available space dips below 1 megabyte, the local alloc file is disabled. In
    either case, local alloc is re-enabled 30 seconds after the event, or when
    an appropriate amount of bits is seen in the primary bitmap.
    Signed-off-by: default avatarMark Fasheh <mfasheh@suse.com>
localalloc.h 1.86 KB