Re: memory management and the status of

Chris Wedgwood (chris@cybernet.co.nz)
Sun, 6 Sep 1998 09:58:59 +1200


On Sat, Sep 05, 1998 at 07:04:26PM +0100, Alan Cox wrote:

> Doubtful indeed. Your choppy mp3 points to different problems. Free
> memory is wasted memory.

This depends on how you define `free'.

Right now, it looks like free is defined as unallocated - I think it
would be better defined as `unused' (although I can't tell you how to
determine that, or how to define unused).

Migrating unused code and data pages from applications that have been
running for a bit seems like a good idea to me, these pages are often
touched when applications init, and then very infrequently (if every)
again, so this RAM would be better used as buffer-cache.

With 256M of ram, I pretty much never hit swap unless I try really
hard, however, when there has been a lot going on, I find there are
many applications who have pages allocated not doing much with them.

Forcing these pages _out_ (over-commit & touch), and then letting
things stabilise, does indeed seem to help disk performance with
things like `make dep' and find blah, etc.

-Chris

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