Re: mmap vs fs cache

From: Howard Chu
Date: Tue Mar 05 2013 - 18:55:11 EST


Howard Chu wrote:
2 questions:
why is there data in the FS cache that isn't owned by (the mmap of) the
process that caused it to be paged in in the first place?
is there a tunable knob to discourage the page cache from stealing from the
process?

This Unmapped page cache control http://lwn.net/Articles/436010/ sounds like it might have been helpful here. I.e., having a way to prioritize so that unmapped cache pages get reclaimed in preference to mapped pages could help. Though I still don't understand why these pages in the cache aren't mapped in the first place.

--
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/
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