Re: [PATCH -mm] vmscan: protect a fraction of file backed mapped pages from reclaim

Christoph Lameter
2009-05-12T17:21:48Z

On Tue, 12 May 2009, Rik van Riel wrote:

> The patch that only allows active file pages to be deactivated
> if the active file LRU is larger than the inactive file LRU should
> protect the working set from being evicted due to streaming IO.

Streaming I/O means access once? What exactly are the criteria for a page
to be part of streaming I/O? AFAICT the definition is more dependent on
the software running than on a certain usage pattern discernible to the
VM. Software may after all perform multiple scans over a stream of data or
go back to prior locations in the file.