linux-kernel - Re: [RFC PATCH 3/9] mm: zswap: refactor limit checking from zswap

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Date: Wed, 27 Mar 2024 15:30:41 -0700
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Chengming Zhou <chengming.zhou@...ux.dev>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Johannes Weiner <hannes@...xchg.org>, 
	Nhat Pham <nphamcs@...il.com>, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 3/9] mm: zswap: refactor limit checking from zswap_store()

On Tue, Mar 26, 2024 at 7:42 PM Chengming Zhou <chengming.zhou@...ux.dev> wrote:
>
> On 2024/3/26 07:50, Yosry Ahmed wrote:
> > Refactor limit and acceptance threshold checking outside of
> > zswap_store(). This code will be moved around in a following patch, so
> > it would be cleaner to move a function call around.
> >
> > Signed-off-by: Yosry Ahmed <yosryahmed@...gle.com>
> > ---
> >  mm/zswap.c | 32 ++++++++++++++++----------------
> >  1 file changed, 16 insertions(+), 16 deletions(-)
> >
> > diff --git a/mm/zswap.c b/mm/zswap.c
> > index ff1975afb7e3d..6b890c8590ef7 100644
> > --- a/mm/zswap.c
> > +++ b/mm/zswap.c
> > @@ -1415,6 +1415,21 @@ static void zswap_fill_page(void *ptr, unsigned long value)
> >       memset_l(page, value, PAGE_SIZE / sizeof(unsigned long));
> >  }
> >
> > +static bool zswap_check_limit(void)
> > +{
> > +     unsigned long cur_pages = zswap_total_pages();
> > +     unsigned long thr = zswap_accept_thr_pages();
> > +     unsigned long max_pages = zswap_max_pages();
> > +
> > +     if (cur_pages >= max_pages) {
> > +             zswap_pool_limit_hit++;
> > +             zswap_pool_reached_full = true;
> > +     } else if (zswap_pool_reached_full && cur_pages <= thr) {
> > +             zswap_pool_reached_full = false;
> > +     }
> > +     return !zswap_pool_reached_full;
>
> nit: Then we use "!zswap_check_limit()" below, double negation looks complex,
> should we change to zswap_should_reject() or something?

Good point. Will rename it in the next version.

Thanks!