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b=Z1gFlxcwZtWV6mPCa6DoyMtNy+ryKBDf7VvGjK1BHFSa7zvNqAfMh0onxw6Esp6QA PdtPaEq244NK/VR1baqWWmr8Jm5lRiiOFlxLy2BJ7+L/3dh8ky56lsuVQ8qPWv9USw Fwx2xeEIeFlW+EmLzc4lDe+1kcdZz9NegjmvJzwVdrcqyAomgfUR+EfajNg58N06A/ pR9Q+uxTUj59w9eCDo3wfS4g4NZHs3j3oXAv+Xuzc/pGvsiAM6GhhJFfnju+oGBDou nnbyNOrGIxWsBdHElN/Q4Dk6etROiiRyPNGkSwzuM6j7bLC4/rAgVHGYdzoj9yHVFI BOLZTacLYrKLA== Date: Tue, 19 Mar 2024 18:17:07 +0200 From: Mike Rapoport To: Baoquan He Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, linuxppc-dev@lists.ozlabs.org, akpm@linux-foundation.org Subject: Re: [PATCH 4/6] mm/mm_init.c: remove meaningless calculation of zone->managed_pages in free_area_init_core() Message-ID: References: <20240318142138.783350-1-bhe@redhat.com> <20240318142138.783350-5-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240318142138.783350-5-bhe@redhat.com> X-Rspamd-Queue-Id: 842D1A0028 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: a644z9n4qf3tsx8puotzaedd3777dk6d X-HE-Tag: 1710865094-802677 X-HE-Meta: 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 m/nj6g3c SM3mNa2IbhYGgxb4fNtDv3n0RIyGicarhYr3TWjO0f8GFab49MPDTHfrAwJQ85ZIlbQ4g+Kl47Et9+ZDgjmVTCUFlAN3Tx0qNfkoDThpE8/rTDmFP2yBvE+t4Qmw3ywn6wBVdeWS49sHrQELGedMSiNoN4AvV/EhIJtXn0AH/ZZ8DxCXBGIgYNiGmLVQnyLR/1mr9/x8OoyWA0IAnRJxIjnU3++3FCQ5aGjJtfWAjRaQlyHkOfEZ4SdL/OlaZ4rmJvUwV X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Mar 18, 2024 at 10:21:36PM +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), directly set zone->present_pages to > zone->managed_pages. It will be adjusted in mem_init(). Do you mean "set zone->managed_pages to zone->present_pages"? I think we can just set zone->managed_pages to 0 in free_area_init_core(). Anyway it will be reset before the first use. > 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. > > Signed-off-by: Baoquan He > --- > mm/mm_init.c | 38 ++++++-------------------------------- > 1 file changed, 6 insertions(+), 32 deletions(-) > > diff --git a/mm/mm_init.c b/mm/mm_init.c > index c57a7fc97a16..55a2b886b7a6 100644 > --- a/mm/mm_init.c > +++ b/mm/mm_init.c > @@ -1584,41 +1584,14 @@ static void __init free_area_init_core(struct pglist_data *pgdat) > > for (j = 0; j < MAX_NR_ZONES; j++) { > struct zone *zone = pgdat->node_zones + j; > - unsigned long size, freesize, memmap_pages; > - > - size = zone->spanned_pages; > - freesize = zone->present_pages; > - > - /* > - * Adjust freesize so that it accounts for how much memory > - * is used by this zone for memmap. This affects the watermark > - * and per-cpu initialisations > - */ > - memmap_pages = calc_memmap_size(size, freesize); > - if (!is_highmem_idx(j)) { > - if (freesize >= memmap_pages) { > - freesize -= memmap_pages; > - if (memmap_pages) > - pr_debug(" %s zone: %lu pages used for memmap\n", > - zone_names[j], memmap_pages); > - } else > - pr_warn(" %s zone: %lu memmap pages exceeds freesize %lu\n", > - zone_names[j], memmap_pages, freesize); > - } > - > - if (!is_highmem_idx(j)) > - nr_kernel_pages += freesize; > - /* Charge for highmem memmap if there are enough kernel pages */ > - else if (nr_kernel_pages > memmap_pages * 2) > - nr_kernel_pages -= memmap_pages; > - nr_all_pages += freesize; > + unsigned long size = zone->spanned_pages; > > /* > - * Set an approximate value for lowmem here, it will be adjusted > - * when the bootmem allocator frees pages into the buddy system. > - * And all highmem pages will be managed by the buddy system. > + * Set the zone->managed_pages as zone->present_pages roughly, it > + * be zeroed out and reset when memblock allocator frees pages into > + * buddy system. > */ > - zone_init_internals(zone, j, nid, freesize); > + zone_init_internals(zone, j, nid, zone->present_pages); > > if (!size) > continue; > @@ -1915,6 +1888,7 @@ void __init free_area_init(unsigned long *max_zone_pfn) > check_for_memory(pgdat); > } > > + calc_nr_kernel_pages(); > memmap_init(); > > /* disable hash distribution for systems with a single node */ > -- > 2.41.0 > -- Sincerely yours, Mike.