Re: Performance regressions in "boot_time" tests in Linux 5.8 Kernel

["bhe@redhat.com" <bhe@redhat.com>]

On 11/20/20 at 03:11am, Rahul Gopakumar wrote:
> Hi Baoquan,
> 
> To which commit should we apply the draft patch. We tried applying
> the patch to the commit 3e4fb4346c781068610d03c12b16c0cfb0fd24a3
> (the one we used for applying the previous patch) but it fails.

I tested on 5.10-rc3+. You can append below change to the old patch in
your testing kernel.

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index fa6076e1a840..5e5b74e88d69 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -448,6 +448,8 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
 	if (end_pfn < pgdat_end_pfn(NODE_DATA(nid)))
 		return false;
 
+	if (NODE_DATA(nid)->first_deferred_pfn != ULONG_MAX)
+		return true;
 	/*
 	 * We start only with one section of pages, more pages are added as
 	 * needed until the rest of deferred pages are initialized.