Re: [PATCH v2 2/4] mm: make the threshold of enabling THP configurable

From: Cong Wang
Date: Tue Jun 21 2011 - 23:07:31 EST

ä 2011å06æ22æ 09:23, David Rientjes åé:
On Tue, 21 Jun 2011, Amerigo Wang wrote:

Don't hard-code 512M as the threshold in kernel, make it configruable,
and set 512M by default.

And print info when THP is disabled automatically on small systems.

V2: Add more description in help messages, correct some typos,
print the mini threshold too.

I like the printk that notifies users why THP was disabled because it
could potentially be a source of confusion (and fixing the existing typos
in hugepage_init() would also be good). However, I disagree that we need
to have this as a config option: you either want the feature for your
systems or you don't. Perhaps add a "transparent_hugepage=force" option
that will act as "always" but also force it to be enabled in all
scenarios, even without X86_FEATURE_PSE, that will override all the logic
that thinks it knows better?

I think that is overkill, because we can still enable THP via /sys
for small systems.

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