On 02.09.24 14:24, Rong Qianfeng wrote:
Reserved pages are basically non-lru pages. This kind of memory can't be
used as migration sources and targets, skip it can bring some performance
benefits.
Any numbers? :)
Because some drivers may also use PG_reserved, we just set PB_migrate_skip
for those clustered reserved bootmem during memory initialization.
Signed-off-by: Rong Qianfeng <rongqianfeng@xxxxxxxx>
---
include/linux/pageblock-flags.h | 13 +++++++++++
mm/compaction.c | 40 +++++++++++++++++++++++++++++++++
mm/mm_init.c | 14 ++++++++++++
mm/page_alloc.c | 7 ++++++
4 files changed, 74 insertions(+)
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index fc6b9c87cb0a..63c5b0c69c1a 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -86,6 +86,11 @@ void set_pfnblock_flags_mask(struct page *page,
set_pfnblock_flags_mask(page, (1 << PB_migrate_skip), \
page_to_pfn(page), \
(1 << PB_migrate_skip))
+
+extern void set_pageblock_skip_range(unsigned long start_pfn,
+ unsigned long end_pfn);
two tabs indentation on the second line please. Applies to all others as
well.
+extern void clear_pageblock_skip_range(unsigned long start_pfn,
+ unsigned long end_pfn);
#else
static inline bool get_pageblock_skip(struct page *page)
{
@@ -97,6 +102,14 @@ static inline void clear_pageblock_skip(struct page *page)
static inline void set_pageblock_skip(struct page *page)
{
}
+static inline void set_pageblock_skip_range(unsigned long start_pfn,
+ unsigned long end_pfn)
+{
+}
+static inline void clear_pageblock_skip_range(unsigned long start_pfn,
+ unsigned long end_pfn)
+{
+}
[...]
/*
* Compound pages of >= pageblock_order should consistently be skipped until
* released. It is always pointless to compact pages of such order (if they are
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 4ba5607aaf19..8b7dc8e00bf1 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -768,6 +768,13 @@ void __meminit reserve_bootmem_region(phys_addr_t start,
__SetPageReserved(page);
}
}
+
+ /*
+ * Set PB_migrate_skip for reserved region. for cma memory
+ * and the memory released by free_reserved_area(), we will
+ * clear PB_migrate_skip when they are initialized.
+ */
+ set_pageblock_skip_range(start_pfn, end_pfn);
}
/* If zone is ZONE_MOVABLE but memory is mirrored, it is an overlapped init */
@@ -2236,6 +2243,13 @@ void __init init_cma_reserved_pageblock(struct page *page)
set_page_count(p, 0);
} while (++p, --i);
+ /*
+ * We set the PB_migrate_skip in
+ * reserve_bootmem_region() for cma
+ * memory, clear it now.
You can fit this easily into less lines
+ */
+ clear_pageblock_skip(page);
+
set_pageblock_migratetype(page, MIGRATE_CMA);
set_page_refcounted(page);
/* pages were reserved and not allocated */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b98f9bb28234..a7729dac0198 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5887,6 +5887,13 @@ unsigned long free_reserved_area(void *start, void *end, int poison, const char
if (pages && s)
pr_info("Freeing %s memory: %ldK\n", s, K(pages));
+ /*
+ * Clear PB_migrate_skip if the memory have released
+ * to the buddy system.
+ */
... after freeing the memory to the buddy."
And maybe
if (pages) {
if (s)
pr_info("Freeing %s memory: %ldK\n", s, K(pages));
clear_pageblock_skip_range(...)
}
+ clear_pageblock_skip_range(page_to_pfn(virt_to_page(start)),
+ page_to_pfn(virt_to_page(end)));
+
PHYS_PFN(virt_to_phys(start)) might look a bit nicer, not need to
get pages involved. virt_to_pfn might be even better(), but it's
not available on all archs I think.
What about free_reserved_page() ? There might be more, though
(kimage_free_pages()). You have to take a look at all functions where we
clear PageReserved.
--
Cheers,
David / dhildenb
