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().
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 <bhe@redhat.com>
---
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 */
--
2.41.0On 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 <bhe@redhat.com>
> ---
> 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.
On 03/19/24 at 06:17pm, Mike Rapoport wrote:
> 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"?
Hmm, maybe 'set zone->managed_pages as zone->present_pages'
or
'assign zone->present_pages to zone->managed_pages'
which is more precise.
Wwill update.
>
> 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.
Yeah, setting to 0 is also fine. I thougt of 0 ever. Considering
zone->present_pages is closer value to actual zone->managed_pages
than 0, and it may be needed in the future in some way before
mem_init(). If no strong objection, I will keep the assigning
'zone->present_pages' to 'zone->managed_pages'.
Thanks again for careful reviewing.
On 03/20/24 at 04:18pm, Baoquan He wrote: > On 03/19/24 at 06:17pm, Mike Rapoport wrote: > > 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"? > > Hmm, maybe 'set zone->managed_pages as zone->present_pages' > or > 'assign zone->present_pages to zone->managed_pages' > which is more precise. > > Wwill update. > > > > > 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. Rethink about this, it's better to set zone->managed_pages to 0 because there isn't any page added to buddy. Will update. > > Yeah, setting to 0 is also fine. I thougt of 0 ever. Considering > zone->present_pages is closer value to actual zone->managed_pages > than 0, and it may be needed in the future in some way before > mem_init(). If no strong objection, I will keep the assigning > 'zone->present_pages' to 'zone->managed_pages'. > > Thanks again for careful reviewing. >
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