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References: <20231206033913.1290566-1-judyhsiao@chromium.org>
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From:   Eric Dumazet <edumazet@google.com>
Date:   Wed, 6 Dec 2023 08:34:24 +0100
Message-ID: <CANn89iKiG0oLhkYQj=OkhvcWyR_kfSsot_2zo9hFCm1A7u-tWA@mail.gmail.com>
Subject: Re: [PATCH v2] neighbour: Don't let neigh_forced_gc() disable
 preemption for long
To:     Judy Hsiao <judyhsiao@chromium.org>
Cc:     David Ahern <dsahern@kernel.org>, Simon Horman <horms@kernel.org>,
        Douglas Anderson <dianders@chromium.org>,
        Brian Haley <haleyb.dev@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Joel Granados <joel.granados@gmail.com>,
        Julian Anastasov <ja@ssi.bg>,
        Leon Romanovsky <leon@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
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On Wed, Dec 6, 2023 at 4:39=E2=80=AFAM Judy Hsiao <judyhsiao@chromium.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=3D1000 which expects tasks to be able to schedule in
> with ~1ms latency.
>
> Suggested-by: Douglas Anderson <dianders@chromium.org>
> Signed-off-by: Judy Hsiao <judyhsiao@chromium.org>
>
> ---
>
> Changes in v2:
> - Use ktime_get_ns() for timeout calculation instead of jiffies.

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