Buffer Cache Thrashing

[Wayne Davison]

On Thu, Apr 16, 2009 at 10:44:29PM -0400, Josh Snyder wrote:
> Rsync thrashes my buffer cache when transfering large files.  I see
> that some people worked on this problem about a year ago.  Did they
> find a workable solution?

Some Linux-only work was done, but the patches really revealed that
there needs to be a much better way to ask Linux to not fill up the
cache with the current program's workload since the solution turned
into a pretty big kluge to try to get Linux to do the right thing.
It would be cool if some improvements were done at the OS level to
fix the issue without requiring individual programs to be hacked up.

However, work could be done to cleanup the prior cache-affecting work
and merge together the current patches/drop-cache.diff code with the
later improvements from Tobi Oetiker, but cleaned up to be less
intrusive in the code (e.g. to use more macros instead of tweaking
lots of system calls, which makes it easier to maintain).

..wayne..