Re: [PATCH] Rmap speedup

From: Andrew Morton (
Date: Fri Aug 02 2002 - 15:20:37 EST

Daniel Phillips wrote:
> This patch eliminates about 35% of the raw rmap setup/teardown overhead by
> adopting a new locking interface that allows the add_rmaps to be batched in
> copy_page_range.

Well that's fairly straightforward, thanks. Butt-ugly though ;)

Don't bother doing teardown yet. I have patches which batch
all the zap_page_range activity into 16-page chunks, so we
eventually end up in a single function with 16 virtually-contiguous
pages to release. Adding the batched locking to that will
be simple.

Sigh. I have a test which sends the 2.5.30 VM into a five-minute
coma and which immediately panics latest -ac with pte_chain oom.
Remind me again why all this is worth it?

I'll port your stuff to 2.5 over the weekend, let you know...
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