Re: Doc tweak for huge_pages?

On Fri, Dec 1, 2017 at 10:09 PM, Thomas Munro
<thomas(dot)munro(at)enterprisedb(dot)com> wrote:
>> On 11/30/17 23:35, Thomas Munro wrote:
>>> Hmm. Yeah, it does, but apparently it's not so transparent. So if we
>>> mention that we'd better indicate in the same paragraph that you
>>> probably don't actually want to use it. How about the attached?

Here's a review for v3.

I find that the first paragraph is an improvement as it's more precise.

What I didn't like about the second paragraph is that it pointed out
Linux transparent huge pages too favorably while they are actually
known to cause big (huge?, pardon the pun) issues (as witnessed in
this thread as well). v3 basically says "in Linux it can be
transparent or explicit and explicit is faster than transparent".
Reading that, and seeing that explicit needs tweaking of kernel
parameters and so on, one might very well conclude "I'll use the
slightly-slower-but-still-better-than-nothing transparent version".

So I tried to redo the second paragraph and ended up with the
attached. Rationale for the changes:
* changed "this feature" to "explicitly requesting huge pages" to
contrast with the automatic one described below
* made the wording of Linux THP more negative (but still with some
wiggle room for future kernel versions which might improve THP),
contrasting with the positive explicit request from this GUC
* integrated your mention of other OSes with automatic huge pages
* moved the new text to the last paragraph to lower its importance

What do you think?