On 2023/8/26 03:04, Mike Kravetz wrote:
Now that batching of hugetlb vmemmap optimization processing is possible,
batch the freeing of vmemmap pages. When freeing vmemmap pages for a
hugetlb page, we add them to a list that is freed after the entire batch
has been processed.
This enhances the ability to return contiguous ranges of memory to the
low level allocators.
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
mm/hugetlb_vmemmap.c | 56 ++++++++++++++++++++++++++++++++------------
1 file changed, 41 insertions(+), 15 deletions(-)
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index d5e6b6c76dce..e390170c0887 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -305,11 +305,14 @@ static void vmemmap_restore_pte(pte_t *pte, unsigned long addr,
* @end: end address of the vmemmap virtual address range that we want to
* remap.
* @reuse: reuse address.
+ * @bulk_pages: list to deposit vmemmap pages to be freed in bulk operations
+ * or NULL in non-bulk case;
I'd like to rename bulk_pages to vmemmap_pages. Always add the vmemmap
pages to this list and let the caller (hugetlb_vmemmap_optimize and
hugetlb_vmemmap_optimize_folios) to help us to free them. It will be
clear to me.
*
* Return: %0 on success, negative error code otherwise.
*/
static int vmemmap_remap_free(unsigned long start, unsigned long end,
- unsigned long reuse)
+ unsigned long reuse,
+ struct list_head *bulk_pages)
{
int ret;
LIST_HEAD(vmemmap_pages);
@@ -372,7 +375,14 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end,
}
mmap_read_unlock(&init_mm);
- free_vmemmap_page_list(&vmemmap_pages);
+ /*
+ * if performing bulk operation, do not free pages here.
+ * rather add them to the bulk list
+ */
+ if (!bulk_pages)
+ free_vmemmap_page_list(&vmemmap_pages);
+ else
+ list_splice(&vmemmap_pages, bulk_pages);
Here, always add vmemmap_pages to the list.
return ret;
}
@@ -546,17 +556,9 @@ static bool vmemmap_should_optimize(const struct hstate *h, const struct page *h
return true;
}
-/**
- * hugetlb_vmemmap_optimize - optimize @head page's vmemmap pages.
- * @h: struct hstate.
- * @head: the head page whose vmemmap pages will be optimized.
- *
- * This function only tries to optimize @head's vmemmap pages and does not
- * guarantee that the optimization will succeed after it returns. The caller
- * can use HPageVmemmapOptimized(@head) to detect if @head's vmemmap pages
- * have been optimized.
- */
-void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head)
+static void __hugetlb_vmemmap_optimize(const struct hstate *h,
+ struct page *head,
+ struct list_head *bulk_pages)
Also struct list_head *vmemmap_pages.
{
unsigned long vmemmap_start = (unsigned long)head, vmemmap_end;
unsigned long vmemmap_reuse;
@@ -575,18 +577,42 @@ void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head)
* to the page which @vmemmap_reuse is mapped to, then free the pages
* which the range [@vmemmap_start, @vmemmap_end] is mapped to.
*/
- if (vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse))
+ if (vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse, bulk_pages))
static_branch_dec(&hugetlb_optimize_vmemmap_key);
else
SetHPageVmemmapOptimized(head);
}
+/**
+ * hugetlb_vmemmap_optimize - optimize @head page's vmemmap pages.
+ * @h: struct hstate.
+ * @head: the head page whose vmemmap pages will be optimized.
+ *
+ * This function only tries to optimize @head's vmemmap pages and does not
+ * guarantee that the optimization will succeed after it returns. The caller
+ * can use HPageVmemmapOptimized(@head) to detect if @head's vmemmap pages
+ * have been optimized.
+ */
+void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head)
+{
+ __hugetlb_vmemmap_optimize(h, head, NULL);
Use free_vmemmap_page_list to free vmemmap pages here.
+}
+
+void hugetlb_vmemmap_optimize_bulk(const struct hstate *h, struct page *head,
+ struct list_head *bulk_pages)
+{
+ __hugetlb_vmemmap_optimize(h, head, bulk_pages);
+}
+
void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list)
{
struct folio *folio;
+ LIST_HEAD(vmemmap_pages);
list_for_each_entry(folio, folio_list, lru)
- hugetlb_vmemmap_optimize(h, &folio->page);
+ hugetlb_vmemmap_optimize_bulk(h, &folio->page, &vmemmap_pages);
Directly use __hugetlb_vmemmap_optimize and delete
hugetlb_vmemmap_optimize_bulk.
In the future, we could rename hugetlb_vmemmap_optimize to
hugetlb_vmemmap_optimize_folio,
then, both function names are more consistent. E.g.
1) hugetlb_vmemmap_optimize_folio(): used to free one folio's vmemmap
pages.
2) hugetlb_vmemmap_optimize_folios(): used to free multiple folio's
vmemmap pages.
Thanks.
+
+ free_vmemmap_page_list(&vmemmap_pages);
}
static struct ctl_table hugetlb_vmemmap_sysctls[] = {
