linux-kernel - Re: [PATCH 07/10] bootmem: add free_bootmem

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Message-ID: <20091113211104.GA27945@sequoia.sous-sol.org>
Date:	Fri, 13 Nov 2009 13:11:04 -0800
From:	Chris Wright <chrisw@...s-sol.org>
To:	Pekka Enberg <penberg@...helsinki.fi>
Cc:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
	linux-kernel@...r.kernel.org, chrisw@...s-sol.org,
	dwmw2@...radead.org, joerg.roedel@....com, mingo@...e.hu,
	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>, Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 07/10] bootmem: add free_bootmem_late

* Pekka Enberg (penberg@...helsinki.fi) wrote:
> On Mon, Nov 9, 2009 at 10:13 PM, Pekka Enberg <penberg@...helsinki.fi> wrote:
> >>        for (cursor = start; cursor < end; cursor += BITS_PER_LONG) {
> >> -               unsigned long idx, vec;
> >> +               unsigned long vec;
> >>
> >> -               idx = cursor - start;
> >> -               vec = ~map[idx / BITS_PER_LONG];
> >> +               if (map) {
> >> +                       unsigned long idx = cursor - start;
> >> +                       vec = ~map[idx / BITS_PER_LONG];
> >> +               } else {
> >> +                       if (end - cursor >= BITS_PER_LONG)
> >> +                               vec = ~0UL;
> >
> > Why do we need the above?
> 
> OK, I figured that out. I'm not sure why you want to play tricks with
> "vec" when you could just add a new helper that calls
> __free_pages_bootmem() for the full contiguous page range.

I did it this way since it's simple enough and allows for high-order
frees (these will nearly all be high-order) and keeps the same core
code exercised in each path.  You can't do a higher order free
w/ __free_pages_bootmem() w/out conforming to its requirements.
I don't care either way.

thanks,
-chris
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