linux-kernel - Re: [RFC PATCH] mm: khugepaged: don't carry huge page to the next loop for !CONFIG

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Message-ID: <CAHbLzkrXOM0Ow3YbZnj9RyvTJ8fwaUCzAizOMR5MP=TkxeLywg@mail.gmail.com>
Date:   Tue, 31 Aug 2021 20:46:11 -0700
From:   Yang Shi <shy828301@...il.com>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     Hugh Dickins <hughd@...gle.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux MM <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] mm: khugepaged: don't carry huge page to the next
 loop for !CONFIG_NUMA

On Tue, Aug 31, 2021 at 4:38 PM Kirill A. Shutemov <kirill@...temov.name> wrote:
>
> On Mon, Aug 30, 2021 at 11:49:43AM -0700, Yang Shi wrote:
> > Gently ping...
> >
> > Does this patch make sense? BTW, I have a couple of other khugepaged
> > related patches in my queue. I plan to send them with this patch
> > together. It would be great to hear some feedback before resending
> > this one.
>
> I don't really care for !NUMA optimization. I believe that most of setups
> that benefit from THP has NUMA enabled compile time.

Agreed.

>
> But if you wanna to go this path, make an effort to cleanup other
> artifacts for the !NUMA optimization: the ifdef has to be gone and all
> callers of these helpers has to be revisited. There's more opportunities to
> cleanup. Like it is very odd that khugepaged_prealloc_page() frees the
> page.

Yes, they are gone in this patch. The only remaining for !NUMA is
khugepaged_find_target_node() which just returns 0.

>
>
> --
>  Kirill A. Shutemov