mm: change filecache reclaim policy for CMA [1/1]

PD#SWPL-119

Problem:
High IOW usually happen when start playing 4K video. This
is because codec drvier will using large amount of memory
from CMA pool. And many filecache will be dropped after CMA
allocation finished without considering mapcount of each
file cache page.

Solution:
Check mapcount of filecache for each file pages. And migrate
them if they have high map count. High map count means this
file cache page is shared by many process.

Verify:
verified by ampere

Change-Id: I3e09437286f14a6cd9f7025566eb855dc9ca98d5
Signed-off-by: tao zeng <tao.zeng@amlogic.com>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 62cc6da..5d86ff1 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1304,6 +1304,20 @@ keep:
        return nr_reclaimed;
 }
 
+#ifdef CONFIG_AMLOGIC_CMA
+#define ACTIVE_MIGRATE         3
+#define INACTIVE_MIGRATE       (ACTIVE_MIGRATE * 4)
+static int filecache_need_migrate(struct page *page)
+{
+       if (PageActive(page) && page_mapcount(page) >= ACTIVE_MIGRATE)
+               return 1;
+
+       if (!PageActive(page) && page_mapcount(page) >= INACTIVE_MIGRATE)
+               return 1;
+
+       return 0;
+}
+#endif
 unsigned long reclaim_clean_pages_from_list(struct zone *zone,
                                            struct list_head *page_list)
 {
@@ -1315,12 +1329,33 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
        unsigned long ret, dummy1, dummy2, dummy3, dummy4, dummy5;
        struct page *page, *next;
        LIST_HEAD(clean_pages);
+#ifdef CONFIG_AMLOGIC_CMA
+       LIST_HEAD(high_active_pages);
+       unsigned long nr_high_active = 0;
+       unsigned long nr_normal_pages = 0;
+#endif
 
        list_for_each_entry_safe(page, next, page_list, lru) {
                if (page_is_file_cache(page) && !PageDirty(page) &&
                    !__PageMovable(page)) {
+               #ifdef CONFIG_AMLOGIC_CMA
+                       if (filecache_need_migrate(page)) {
+                               /*
+                                * leaving pages with high map count to migrate
+                                * instead of reclaimed. This can help to avoid
+                                * file cache jolt if reclaim large cma size
+                                */
+                               list_move(&page->lru, &high_active_pages);
+                               nr_high_active++;
+                       } else {
+                               ClearPageActive(page);
+                               list_move(&page->lru, &clean_pages);
+                               nr_normal_pages++;
+                       }
+               #else
                        ClearPageActive(page);
                        list_move(&page->lru, &clean_pages);
+               #endif
                }
        }
 
@@ -1328,6 +1363,11 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
                        TTU_UNMAP|TTU_IGNORE_ACCESS,
                        &dummy1, &dummy2, &dummy3, &dummy4, &dummy5, true);
        list_splice(&clean_pages, page_list);
+#ifdef CONFIG_AMLOGIC_CMA
+       list_splice(&high_active_pages, page_list);
+       pr_debug("high_active:%4ld, normal:%4ld, reclaimed:%4ld\n",
+               nr_high_active, nr_normal_pages, ret);
+#endif
        mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, -ret);
        return ret;
 }