Re: [RFC][PATCH 0/4] VM split active lists

From: Nick Piggin
Date: Wed Mar 10 2004 - 00:33:34 EST

Nick Piggin wrote:

OK, the theory is that mapped pagecache pages are worth more than
unmapped pages. This is a good theory because mapped pages will
usually have far more random access patterns, so pagein *and* pageout
will be much less efficient. Also, applications are probably coded to
be more suited to blocking in read() than a random code / anon memory
page. So a factor of >= 16 wouldn't be out of the question.

Just a followup - there is a small but significant bug in patch
#4/4. In shrink_zone, mapped_ratio should be divided by
nr_active_unmapped. I have this fixed, hugepage compile problems
fixed, and a mapped_page_cost tunable in place of swappiness. So
anyone interested in testing should please ask me for my latest

I'm getting some preliminary numbers now. They're pretty good,
looks like they should be similar to dont-rotate-active-list
which isn't too surprising.

Interestingly, mapped_page_cost of 8 is close to optimal for
swapping-kbuild throughput. Values of 4 and 16 are both worse.
mapped_page_cost is in units of unmapped page cost. Maybe it is
just me, but I find this scheme is more meaningful and provides
more control than swappiness.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at