lkml.org 
[lkml]   [2007]   [Sep]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: VM/VFS bug with large amount of memory and file systems?
    On Mon, 17 Sep 2007 13:11:14 -0400
    Rik van Riel <riel@redhat.com> wrote:

    > > I'm guessing there is no pressure at all on zone_highmem so the
    > > kernel will not try to reclaim pagecache. And because the pagecache
    > > pages are happily sitting there, the buggerheads are pinned and do not
    > > get reclaimed.

    yeah, this got pretty unavoidably broken when we killed the global LRU
    in 2.5.early. It's odd that it took this long for someone to hit it.

    > I've got code for this in RHEL 3, but never bothered to
    > merge it upstream since I thought people with large memory
    > systems would be running 64 bit kernels by now.
    >
    > Obviously I was wrong. Andrew, are you interested in a
    > fix for this problem?
    >
    > IIRC I simply kept a list of all buffer heads and walked
    > that to reclaim pages when the number of buffer heads is
    > too high (and we need memory). This list can be maintained
    > in places where we already hold the lock for the buffer head
    > freelist, so there should be no additional locking overhead
    > (again, IIRC).

    Christoph's slab defragmentation code should permit us to fix this:
    grab a page of buffer_heads off the slab lists, trylock the page,
    strip the buffer_heads. I think that would be a better approach
    if we can get it going because it's more general.
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-09-17 22:19    [W:0.051 / U:0.468 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site