linux-kernel - Re: [PATCH v2 1/3] mm: Shuffle initial free memory

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Date:   Tue, 9 Oct 2018 10:36:14 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Linux MM <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] mm: Shuffle initial free memory

On Tue, Oct 9, 2018 at 4:16 AM Michal Hocko <mhocko@...nel.org> wrote:
>
> On Thu 04-10-18 09:51:37, Dan Williams wrote:
> > On Thu, Oct 4, 2018 at 12:48 AM Michal Hocko <mhocko@...nel.org> wrote:
[..]
> > So the reason front-back randomization is not enough is due to the
> > in-order initial freeing of pages. At the start of that process
> > putting page1 in front or behind page0 still keeps them close
> > together, page2 is still near page1 and has a high chance of being
> > adjacent. As more pages are added ordering diversity improves, but
> > there is still high page locality for the low address pages and this
> > leads to no significant impact to the cache conflict rate. Patch3 is
> > enough to keep the entropy sustained over time, but it's not enough
> > initially.
>
> That should be in the changelog IMHO.

Fair enough, I'll fold that in when I rebase on top of -next.