system/easy-kernel: Update to 6.6.6-mc1

1 files changed, 44 insertions, 0 deletions

diff --git a/system/easy-kernel/0400-reduce-pageblock-size-nonhugetlb.patch b/system/easy-kernel/0400-reduce-pageblock-size-nonhugetlb.patch
new file mode 100644
index 000000000..b32f4ba76
--- /dev/null
+++ b/system/easy-kernel/0400-reduce-pageblock-size-nonhugetlb.patch
@@ -0,0 +1,44 @@
+From: Sultan Alsawaf <sultan@kerneltoast.com>
+Date: Wed, 20 Oct 2021 20:50:11 -0700
+Subject: [PATCH 02/16] ZEN: mm: Lower the non-hugetlbpage pageblock size to
+ reduce scheduling delays
+
+The page allocator processes free pages in groups of pageblocks, where
+the size of a pageblock is typically quite large (1024 pages without
+hugetlbpage support). Pageblocks are processed atomically with the zone
+lock held, which can cause severe scheduling delays on both the CPU
+going through the pageblock and any other CPUs waiting to acquire the
+zone lock. A frequent offender is move_freepages_block(), which is used
+by rmqueue() for page allocation.
+
+As it turns out, there's no requirement for pageblocks to be so large,
+so the pageblock order can simply be reduced to ease the scheduling
+delays and zone lock contention. PAGE_ALLOC_COSTLY_ORDER is used as a
+reasonable setting to ensure non-costly page allocation requests can
+still be serviced without always needing to free up more than one
+pageblock's worth of pages at a time.
+
+This has a noticeable effect on overall system latency when memory
+pressure is elevated. The various mm functions which operate on
+pageblocks no longer appear in the preemptoff tracer, where previously
+they would spend up to 100 ms on a mobile arm64 CPU processing a
+pageblock with preemption disabled and the zone lock held.
+
+Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
+---
+ include/linux/pageblock-flags.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
+index e83c4c095..21b8dfa5d 100644
+--- a/include/linux/pageblock-flags.h
++++ b/include/linux/pageblock-flags.h
+@@ -48,7 +48,7 @@ extern unsigned int pageblock_order;
+ #else /* CONFIG_HUGETLB_PAGE */
+ 
+ /* If huge pages are not used, group by MAX_ORDER_NR_PAGES */
+-#define pageblock_order		MAX_ORDER
++#define pageblock_order		PAGE_ALLOC_COSTLY_ORDER
+ 
+ #endif /* CONFIG_HUGETLB_PAGE */
+