[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <ZgQ99kf4D893Y7-Y@kernel.org>
Date: Wed, 27 Mar 2024 17:40:38 +0200
From: Mike Rapoport <rppt@...nel.org>
To: Baoquan He <bhe@...hat.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, x86@...nel.org,
linuxppc-dev@...ts.ozlabs.org, akpm@...ux-foundation.org
Subject: Re: [PATCH v2 4/6] mm/mm_init.c: remove meaningless calculation of
zone->managed_pages in free_area_init_core()
On Mon, Mar 25, 2024 at 10:56:44PM +0800, Baoquan He wrote:
> Currently, in free_area_init_core(), when initialize zone's field, a
> rough value is set to zone->managed_pages. That value is calculated by
> (zone->present_pages - memmap_pages).
>
> In the meantime, add the value to nr_all_pages and nr_kernel_pages which
> represent all free pages of system (only low memory or including HIGHMEM
> memory separately). Both of them are gonna be used in
> alloc_large_system_hash().
>
> However, the rough calculation and setting of zone->managed_pages is
> meaningless because
> a) memmap pages are allocated on units of node in sparse_init() or
> alloc_node_mem_map(pgdat); The simple (zone->present_pages -
> memmap_pages) is too rough to make sense for zone;
> b) the set zone->managed_pages will be zeroed out and reset with
> acutal value in mem_init() via memblock_free_all(). Before the
> resetting, no buddy allocation request is issued.
>
> Here, remove the meaningless and complicated calculation of
> (zone->present_pages - memmap_pages), initialize zone->managed_pages as 0
> which reflect its actual value because no any page is added into buddy
> system right now. It will be reset in mem_init().
>
> And also remove the assignment of nr_all_pages and nr_kernel_pages in
> free_area_init_core(). Instead, call the newly added calc_nr_kernel_pages()
> to count up all free but not reserved memory in memblock and assign to
> nr_all_pages and nr_kernel_pages. The counting excludes memmap_pages,
> and other kernel used data, which is more accurate than old way and
> simpler, and can also cover the ppc required arch_reserved_kernel_pages()
> case.
>
> And also clean up the outdated code comment above free_area_init_core().
> And free_area_init_core() is easy to understand now, no need to add
> words to explain.
>
> Signed-off-by: Baoquan He <bhe@...hat.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@...nel.org>
> ---
> mm/mm_init.c | 46 +++++-----------------------------------------
> 1 file changed, 5 insertions(+), 41 deletions(-)
Powered by blists - more mailing lists