Re: [PATCH 0/11] Reduce compaction-related stalls and improveasynchronous migration of dirty pages v6

[Andrew Morton]

On Wed, 14 Dec 2011 15:41:22 +0000
Mel Gorman <mgorman@xxxxxxx> wrote:

> Short summary: There are severe stalls when a USB stick using VFAT
> is used with THP enabled that are reduced by this series. If you are
> experiencing this problem, please test and report back and considering
> I have seen complaints from openSUSE and Fedora users on this as well
> as a few private mails, I'm guessing it's a widespread issue. This
> is a new type of USB-related stall because it is due to synchronous
> compaction writing where as in the past the big problem was dirty
> pages reaching the end of the LRU and being written by reclaim.

Overall footprint:

 fs/btrfs/disk-io.c            |    5 
 fs/hugetlbfs/inode.c          |    3 
 fs/nfs/internal.h             |    2 
 fs/nfs/write.c                |    4 
 include/linux/fs.h            |   11 +-
 include/linux/migrate.h       |   23 +++-
 include/linux/mmzone.h        |    4 
 include/linux/vm_event_item.h |    1 
 mm/compaction.c               |    5 
 mm/memory-failure.c           |    2 
 mm/memory_hotplug.c           |    2 
 mm/mempolicy.c                |    2 
 mm/migrate.c                  |  171 +++++++++++++++++++++-----------
 mm/page_alloc.c               |   50 +++++++--
 mm/swap.c                     |   74 ++++++++++++-
 mm/vmscan.c                   |  114 ++++++++++++++++++---
 mm/vmstat.c                   |    2 
 17 files changed, 371 insertions(+), 104 deletions(-)

The line count belies the increase in complexity.

Sigh, this whole hugetlb page thing is just killing us.
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