From: Jesse Brandeburg <jesse.brandeburg@linux.dev>
To: Eric Dumazet <edumazet@google.com>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org, Simon Horman <horms@kernel.org>,
eric.dumazet@gmail.com
Subject: Re: [PATCH v3 net-next 4/5] net: reduce RTNL hold duration in unregister_netdevice_many_notify() (part 1)
Date: Tue, 14 Jan 2025 15:05:53 -0800 [thread overview]
Message-ID: <2d92ca69-b187-48aa-9d2c-4eff80efdf32@linux.dev> (raw)
In-Reply-To: <20250114205531.967841-5-edumazet@google.com>
On 1/14/25 12:55 PM, Eric Dumazet wrote:
> Two synchronize_net() calls are currently done while holding RTNL.
>
> This is source of RTNL contention in workloads adding and deleting
> many network namespaces per second, because synchronize_rcu()
> and synchronize_rcu_expedited() can use 60+ ms in some cases.
>
> For cleanup_net() use, temporarily release RTNL
> while calling the last synchronize_net().
>
> This should be safe, because devices are no longer visible
> to other threads at this point.
>
> In any case, the new netdev_lock() / netdev_unlock()
> infrastructure that we are adding should allow
> to fix potential issues, with a combination
> of a per-device mutex and dev->reg_state awareness.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com
Reviewed-by: Jesse Brandeburg <jbrandeburg@cloudflare.com>
next prev parent reply other threads:[~2025-01-14 23:05 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-14 20:55 [PATCH v3 net-next 0/5] net: reduce RTNL pressure in unregister_netdevice() Eric Dumazet
2025-01-14 20:55 ` [PATCH v3 net-next 1/5] net: expedite synchronize_net() for cleanup_net() Eric Dumazet
2025-01-14 22:57 ` Jesse Brandeburg
2025-01-14 20:55 ` [PATCH v3 net-next 2/5] net: no longer assume RTNL is held in flush_all_backlogs() Eric Dumazet
2025-01-14 23:01 ` Jesse Brandeburg
2025-01-14 20:55 ` [PATCH v3 net-next 3/5] net: no longer hold RTNL while calling flush_all_backlogs() Eric Dumazet
2025-01-14 23:04 ` Jesse Brandeburg
2025-02-10 4:13 ` Kuniyuki Iwashima
2025-01-14 20:55 ` [PATCH v3 net-next 4/5] net: reduce RTNL hold duration in unregister_netdevice_many_notify() (part 1) Eric Dumazet
2025-01-14 23:05 ` Jesse Brandeburg [this message]
2025-01-14 20:55 ` [PATCH v3 net-next 5/5] net: reduce RTNL hold duration in unregister_netdevice_many_notify() (part 2) Eric Dumazet
2025-01-14 23:09 ` Jesse Brandeburg
2025-01-16 3:30 ` [PATCH v3 net-next 0/5] net: reduce RTNL pressure in unregister_netdevice() patchwork-bot+netdevbpf
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