On 2/3/20 5:53 AM, Kirill A. Shutemov wrote:

On Fri, Jan 31, 2020 at 07:40:27PM -0800, John Hubbard wrote:

quoted

diff --git a/mm/gup.c b/mm/gup.c
index c10d0d051c5b..9fe61d15fc0e 100644
--- a/mm/gup.c
+++ b/mm/gup.c

@@ -29,6 +29,19 @@ struct follow_page_context {
 	unsigned int page_mask;
 };
 
+#ifdef CONFIG_DEBUG_VM

Why under CONFIG_DEBUG_VM? There's nothing about this in the cover letter.

Early on, gup_benchmark showed a really significant slowdown from using these 
counters. And I don't doubt that it's still the case.

I'll re-measure and add a short summary and a few numbers to the patch commit
description, and to the v4 cover letter.


thanks,
-- 
John Hubbard
NVIDIA

quoted

+static inline void __update_proc_vmstat(struct page *page,
+					enum node_stat_item item, int count)
+{
+	mod_node_page_state(page_pgdat(page), item, count);
+}
+#else
+static inline void __update_proc_vmstat(struct page *page,
+					enum node_stat_item item, int count)
+{
+}
+#endif
+
 static void hpage_pincount_add(struct page *page, int refs)
 {
 	VM_BUG_ON_PAGE(!hpage_pincount_available(page), page);