linux-kernel - Re: [PATCH] mm/zswap: Improve with alloc

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Date: Thu, 18 Jan 2024 10:03:23 -0800
From: Nhat Pham <nphamcs@...il.com>
To: Ronald Monthero <debug.penguin32@...il.com>
Cc: sjenning@...hat.com, ddstreet@...e.org, vitaly.wool@...sulko.com, 
	akpm@...ux-foundation.org, chrisl@...nel.org, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, Johannes Weiner <hannes@...xchg.org>, 
	Yosry Ahmed <yosryahmed@...gle.com>
Subject: Re: [PATCH] mm/zswap: Improve with alloc_workqueue() call

On Wed, Jan 17, 2024 at 11:13 AM Nhat Pham <nphamcs@...il.com> wrote:
>
> On Tue, Jan 16, 2024 at 5:32 AM Ronald Monthero
> <debug.penguin32@...il.com> wrote:
>
> + Johannes and Yosry
>
> >
> > The core-api create_workqueue is deprecated, this patch replaces
> > the create_workqueue with alloc_workqueue. The previous
> > implementation workqueue of zswap was a bounded workqueue, this
> > patch uses alloc_workqueue() to create an unbounded workqueue.
> > The WQ_UNBOUND attribute is desirable making the workqueue
> > not localized to a specific cpu so that the scheduler is free
> > to exercise improvisations in any demanding scenarios for
> > offloading cpu time slices for workqueues.
>
> nit: extra space between paragraph would be nice.
>
> > For example if any other workqueues of the same primary cpu
> > had to be served which are WQ_HIGHPRI and WQ_CPU_INTENSIVE.
> > Also Unbound workqueue happens to be more efficient
> > in a system during memory pressure scenarios in comparison
> >  to a bounded workqueue.
> >
> > shrink_wq = alloc_workqueue("zswap-shrink",
> >                      WQ_UNBOUND|WQ_MEM_RECLAIM, 1);
> >
> > Overall the change suggested in this patch should be
> > seamless and does not alter the existing behavior,
> > other than the improvisation to be an unbounded workqueue.
> >
> > Signed-off-by: Ronald Monthero <debug.penguin32@...il.com>
> > ---
> >  mm/zswap.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/zswap.c b/mm/zswap.c
> > index 74411dfdad92..64dbe3e944a2 100644
> > --- a/mm/zswap.c
> > +++ b/mm/zswap.c
> > @@ -1620,7 +1620,8 @@ static int zswap_setup(void)
> >                 zswap_enabled = false;
> >         }
> >
> > -       shrink_wq = create_workqueue("zswap-shrink");
> > +       shrink_wq = alloc_workqueue("zswap-shrink",
> > +                       WQ_UNBOUND|WQ_MEM_RECLAIM, 1);
>

[...]

> >         if (!shrink_wq)
> >                 goto fallback_fail;
> >
> > --
> > 2.34.1
> >

FWIW:
Acked-by: Nhat Pham <nphamcs@...il.com>