Re: [RFC] mm: show message when updating min_free_kbytes in thp

Han Pingtian
2014-01-05T00:35:10Z

On Fri, Jan 03, 2014 at 10:17:54AM -0800, Dave Hansen wrote:
> On 01/02/2014 07:33 PM, Han Pingtian wrote:
> > @@ -130,8 +130,11 @@ static int set_recommended_min_free_kbytes(void)
> > (unsigned long) nr_free_buffer_pages() / 20);
> > recommended_min <<= (PAGE_SHIFT-10);
> >
> > - if (recommended_min > min_free_kbytes)
> > + if (recommended_min > min_free_kbytes) {
> > + pr_info("raising min_free_kbytes from %d to %d to help transparent hugepage allocations\n",
> > + min_free_kbytes, recommended_min);
> > min_free_kbytes = recommended_min;
> > + }
> > setup_per_zone_wmarks();
> > return 0;
> > }
>
> I know I gave you that big bloated string, but 108 columns is a _wee_
> bit over 80. :)
>
> Otherwise, I do like the new message

Thanks. This is the new version:

>From f4d085a880dfae7638b33c242554efb0afc0852b Mon Sep 17 00:00:00 2001
From: Han Pingtian <hanpt@linux.vnet.ibm.com>
Date: Fri, 3 Jan 2014 11:10:49 +0800
Subject: [PATCH] mm: show message when raising min_free_kbytes in THP

min_free_kbytes may be raised during THP's initialization. Sometimes,
this will change the value being set by user. Showing message will
clarify this confusion.

Showing the old value of min_free_kbytes according to Dave Hansen's
suggestion. This will give user the chance to restore old value of
min_free_kbytes.

Signed-off-by: Han Pingtian <hanpt@linux.vnet.ibm.com>
---
mm/huge_memory.c | 6 +++++-
1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 7de1bf8..7910360 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -130,8 +130,12 @@ static int set_recommended_min_free_kbytes(void)
(unsigned long) nr_free_buffer_pages() / 20);
recommended_min <<= (PAGE_SHIFT-10);

- if (recommended_min > min_free_kbytes)
+ if (recommended_min > min_free_kbytes) {
+ pr_info("raising min_free_kbytes from %d to %d "
+ "to help transparent hugepage allocations\n",
+ min_free_kbytes, recommended_min);
min_free_kbytes = recommended_min;
+ }
setup_per_zone_wmarks();
return 0;
}
--
1.7.7.6