Re: [PATCH 1/7] ksm: add some comments

From: Hugh Dickins
Date: Fri Feb 22 2013 - 15:51:18 EST

On Fri, 22 Feb 2013, Ric Mason wrote:
> What's the root reason merge_across_nodes setting just can be changed only
> when there are no ksm shared pages in system?

Simplicity. Why add code (moving nodes from tree to tree, handling
the collisions) for a rare case that doesn't need to be fast?

> Can they be unmerged and merged again during ksmd scan?

That's more or less what happens, isn't it? Perhaps you're
asking why the admin has to echo 2 >run; echo 0 >merge; echo 1 >run
instead of that all happening automatically inside the echo 0 > merge?

If I'd implemented it myself, I might have chosen to do it that way;
but neither I nor other reviewers felt strongly enough to change that,
though we could do so.

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