linux-kernel - Re: [PATCH v2] neighbour: Don't let neigh_forced

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Message-ID: <CANn89iKiG0oLhkYQj=OkhvcWyR_kfSsot_2zo9hFCm1A7u-tWA@mail.gmail.com>
Date:   Wed, 6 Dec 2023 08:34:24 +0100
From:   Eric Dumazet <edumazet@...gle.com>
To:     Judy Hsiao <judyhsiao@...omium.org>
Cc:     David Ahern <dsahern@...nel.org>, Simon Horman <horms@...nel.org>,
        Douglas Anderson <dianders@...omium.org>,
        Brian Haley <haleyb.dev@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Joel Granados <joel.granados@...il.com>,
        Julian Anastasov <ja@....bg>,
        Leon Romanovsky <leon@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH v2] neighbour: Don't let neigh_forced_gc() disable
 preemption for long

On Wed, Dec 6, 2023 at 4:39 AM Judy Hsiao <judyhsiao@...omium.org> wrote:
>
> We are seeing cases where neigh_cleanup_and_release() is called by
> neigh_forced_gc() many times in a row with preemption turned off.
> When running on a low powered CPU at a low CPU frequency, this has
> been measured to keep preemption off for ~10 ms. That's not great on a
> system with HZ=1000 which expects tasks to be able to schedule in
> with ~1ms latency.
>
> Suggested-by: Douglas Anderson <dianders@...omium.org>
> Signed-off-by: Judy Hsiao <judyhsiao@...omium.org>
>
> ---
>
> Changes in v2:
> - Use ktime_get_ns() for timeout calculation instead of jiffies.

SGTM, thanks.
Reviewed-by: Eric Dumazet <edumazet@...gle.com>