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References: <20220830081457.118960-1-aneesh.kumar@linux.ibm.com>
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From:   Wei Xu <weixugc@google.com>
Date:   Tue, 30 Aug 2022 08:48:22 -0700
Message-ID: <CAAPL-u9HDu4Kk23S+mTueCfnHG7ujQJH5zqgkwmyAN52et26SA@mail.gmail.com>
Subject: Re: [PATCH mm-unstable] mm/demotion: Make toptier_distance inclusive
 upper bound of toptiers
To:     "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc:     Linux MM <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Huang Ying <ying.huang@intel.com>,
        Yang Shi <shy828301@gmail.com>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Tim C Chen <tim.c.chen@intel.com>,
        Michal Hocko <mhocko@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Hesham Almatary <hesham.almatary@huawei.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Alistair Popple <apopple@nvidia.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Johannes Weiner <hannes@cmpxchg.org>, jvgediya.oss@gmail.com,
        Bharata B Rao <bharata@amd.com>
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On Tue, Aug 30, 2022 at 1:15 AM Aneesh Kumar K.V
<aneesh.kumar@linux.ibm.com> wrote:
>
> Based on suggestion from Wei Xu <weixugc@google.com>, having an
> inclusive upper bound is found simpler.
>
> Fixes: mm/demotion: Update node_is_toptier to work with memory tiers
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> ---
>  mm/memory-tiers.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
> index c4bd6d052a33..c82eb0111383 100644
> --- a/mm/memory-tiers.c
> +++ b/mm/memory-tiers.c
> @@ -179,7 +179,7 @@ bool node_is_toptier(int node)
>                 toptier = true;
>                 goto out;
>         }
> -       if (memtier->adistance_start < top_tier_adistance)
> +       if (memtier->adistance_start <= top_tier_adistance)
>                 toptier = true;
>         else
>                 toptier = false;
> @@ -361,7 +361,8 @@ static void establish_demotion_targets(void)
>                          * abstract distance below the max value of this memtier

below -> up to ?  Looks good to me otherwise.

Wei

>                          * is considered toptier.
>                          */
> -                       top_tier_adistance = memtier->adistance_start + MEMTIER_CHUNK_SIZE;
> +                       top_tier_adistance = memtier->adistance_start +
> +                                               MEMTIER_CHUNK_SIZE - 1;
>                         break;
>                 }
>         }
> --
> 2.37.2
>