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

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Date:   Tue, 5 Dec 2023 20:43:44 -0700
From:   David Ahern <dsahern@...nel.org>
To:     Judy Hsiao <judyhsiao@...omium.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Simon Horman <horms@...nel.org>
Cc:     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 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@...omium.org>
> Signed-off-by: Judy Hsiao <judyhsiao@...omium.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@...nel.org>