APPLIED(F/U): [PATCH] UBUNTU: SAUCE: mm/page_alloc.c: disable memory reclaim watermark boosting by default

[Andrea Righi]

On Fri, Mar 27, 2020 at 07:46:49PM +0100, Andrea Righi wrote:
> BugLink: https://bugs.launchpad.net/bugs/1861359
> 
> High watermark boosting can cause large swap activity under certain
> memory intensive workloads, making the system very unresponsive (screen
> does not refresh, keyboard not responding, etc.).
> 
> Disable this feature by default to prevent potential large swap
> activity.
> 
> Signed-off-by: Sultan Alsawaf <sultan.alsawaf at canonical.com>
> Signed-off-by: Andrea Righi <andrea.righi at canonical.com>
> ---
>  mm/page_alloc.c | 13 -------------
>  1 file changed, 13 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index d387ca74cb5a..7ab52a62c5ef 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -315,20 +315,7 @@ compound_page_dtor * const compound_page_dtors[] = {
>  
>  int min_free_kbytes = 1024;
>  int user_min_free_kbytes = -1;
> -#ifdef CONFIG_DISCONTIGMEM
> -/*
> - * DiscontigMem defines memory ranges as separate pg_data_t even if the ranges
> - * are not on separate NUMA nodes. Functionally this works but with
> - * watermark_boost_factor, it can reclaim prematurely as the ranges can be
> - * quite small. By default, do not boost watermarks on discontigmem as in
> - * many cases very high-order allocations like THP are likely to be
> - * unsupported and the premature reclaim offsets the advantage of long-term
> - * fragmentation avoidance.
> - */
>  int watermark_boost_factor __read_mostly;
> -#else
> -int watermark_boost_factor __read_mostly = 15000;
> -#endif
>  int watermark_scale_factor = 10;
>  
>  static unsigned long nr_kernel_pages __initdata;
> -- 
> 2.25.1
> 
>