linux-kernel - Re: [PATCH v2] mm/min_free_kbytes: modify min_free

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Date:   Wed, 21 Jun 2023 16:17:22 +0800
From:   liuq <liuq131@...natelecom.cn>
To:     akpm@...ux-foundation.org, "Huang, Ying" <ying.huang@...el.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mm/min_free_kbytes: modify min_free_kbytes calculation
 rules


在 2023/6/21 16:09, liuq 写道:
> Hi, Liuq,
>
> Thanks for updated patch.
>
> liuq <liuq131@...natelecom.cn> writes:
>
> > The current calculation of min_free_kbytes only uses ZONE_DMA and
> > ZONE_NORMAL pages,but the ZONE_MOVABLE zone->_watermark[WMARK_MIN]
> > will also divide part of min_free_kbytes.This will cause the min
> > watermark of ZONE_NORMAL to be too small in the presence of 
> ZONE_MOVEABLE.
> >
> > __GFP_HIGH and PF_MEMALLOC allocations usually don't need moveable
> > zone pages, so just like ZONE_HIGHMEM, cap pages_min to a small
> > value in __setup_per_zone_wmarks.
>
> Please list the test result of your patch.  That is, WMARK_MIN before
> and after your patch in a system with large ZONE_MOVABLE.
>
Hi Huang, Ying

Thank you very much for your review and suggestions. I will send another 
version later.

Best Regards,

liuq

> > Signed-off-by: liuq <liuq131@...natelecom.cn>
> > ---
> >  mm/page_alloc.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 47421bedc12b..608384712a89 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -6364,7 +6364,7 @@ static void __setup_per_zone_wmarks(void)
> >
> >          /* Calculate total number of !ZONE_HIGHMEM pages */
> >          for_each_zone(zone) {
> > -                if (!is_highmem(zone))
> > +                if (!is_highmem(zone) || zone_idx(zone) != 
> ZONE_MOVABLE)
> >                          lowmem_pages += zone_managed_pages(zone);
> >          }
> >
> > @@ -6374,7 +6374,7 @@ static void __setup_per_zone_wmarks(void)
> >                  spin_lock_irqsave(&zone->lock, flags);
> >                  tmp = (u64)pages_min * zone_managed_pages(zone);
> >                  do_div(tmp, lowmem_pages);
> > -                if (is_highmem(zone)) {
> > +                if (is_highmem(zone) || zone_idx(zone) == 
> ZONE_MOVABLE) {
> >                          /*
> >                           * __GFP_HIGH and PF_MEMALLOC allocations 
> usually don't
> >                           * need highmem pages, so cap pages_min to 
> a small
>                                 ~~~~~~~
>
> Change the comments above too?
>
> Best Regards,
> Huang, Ying
>