Rik van Riel wrote:
> On Sun, 22 Aug 2004, Con Kolivas wrote:
> 
> 
>>Added since 2.6.8.1-ck3:
>>+mapped_watermark.diff
> 
> 
> Sounds like a bad idea for file servers ;)
> 
> Wouldn't it be better to lazily move these cached pages to
> a "cached" list like the BSDs have, and reclaim it immediately
> when the memory is needed for something else ?
> 
> It should be easy enough to keep the cached data around and
> still have the cache pages easily reclaimable.

Sounds like a good idea. Would this leave us with large buddies though? 
Also with file caching it tends to do very little so the ram does indeed 
fill up still. Furthermore, setting mapped to 0 basically disables it 
anyway so that shouldn't be an issue. Currently file servers are 
recommended to tune the "swappiness" value to 100 in the same manner.

This is the buddy condition the machine looks like after it's been 
running for days with this patch in situ.

cat /proc/buddyinfo
Node 0, zone      DMA     15     14     10     11     13     11      9 
     5      3      1      0
Node 0, zone   Normal  15778  17800   6885    722     14      1      3 
     0      0      1      0

Just FYI here's the current version of the patch.

Cheers,
Con

  include/linux/mmzone.h |    3 +
  include/linux/swap.h   |    2 -
  include/linux/sysctl.h |    2 -
  kernel/sysctl.c        |    8 ++--
  mm/page_alloc.c        |    5 ++
  mm/vmscan.c            |   98 
+++++++++++++++++++++++--------------------------
  6 files changed, 59 insertions(+), 59 deletions(-)