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Message-ID: <2fea2908-69a5-4c6d-ad27-94f48f2f2586@kernel.org>
Date:   Tue, 5 Dec 2023 20:43:44 -0700
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Subject: Re: [PATCH v2] neighbour: Don't let neigh_forced_gc() disable
 preemption for long
Content-Language: en-US
To:     Judy Hsiao <judyhsiao@chromium.org>,
        Eric Dumazet <edumazet@google.com>,
        Simon Horman <horms@kernel.org>
Cc:     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
References: <20231206033913.1290566-1-judyhsiao@chromium.org>
From:   David Ahern <dsahern@kernel.org>
In-Reply-To: <20231206033913.1290566-1-judyhsiao@chromium.org>
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On 12/5/23 8:38 PM, Judy Hsiao 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@chromium.org>
> Signed-off-by: Judy Hsiao <judyhsiao@chromium.org>
> 
> ---
> 
> Changes in v2:
> - Use ktime_get_ns() for timeout calculation instead of jiffies.
> 
>  net/core/neighbour.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 


Reviewed-by: David Ahern <dsahern@kernel.org>