netdev - Re: [PATCH net-next 00/12] mlxsw: Remove RTNL from route insertion path

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Message-Id: <20200222.212516.1016463361000574214.davem@davemloft.net>
Date:   Sat, 22 Feb 2020 21:25:16 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     idosch@...sch.org
Cc:     netdev@...r.kernel.org, jiri@...lanox.com, mlxsw@...lanox.com,
        idosch@...lanox.com
Subject: Re: [PATCH net-next 00/12] mlxsw: Remove RTNL from route insertion
 path

From: Ido Schimmel <idosch@...sch.org>
Date: Fri, 21 Feb 2020 19:54:03 +0200

> From: Ido Schimmel <idosch@...lanox.com>
> 
> This patch set removes RTNL from the route insertion path in mlxsw in
> order to reduce the control plane latency: the time it takes to push
> routes from user space to the kernel and mlxsw.
> 
> Up until now mlxsw did not have a lock to protect its shared router data
> structures and instead relied on RTNL. While this was simple and worked,
> it resulted in large control plane latencies as RTNL was heavily
> contended - by both the task receiving the netlink messages from user
> space and the mlxsw workqueue that programs the routes to the device.
> 
> By removing RTNL and introducing a new router mutex, this patch set
> reduces the control plane latency by ~80%. A single mutex is added as
> inside mlxsw there is not a lot of concurrency. In addition, a more
> fine-grained locking scheme is much more error-prone.
> 
> Patches #1-#6 are preparations. They add needed locking in NVE and
> multicast routing code instead of relying on RTNL
> Patch #7 introduces the new mutex
> Patches #8-#12 gradually take the lock in various entry points into the
> routing code
> Patch #13 removes RTNL in places where it is no longer required

Series applied, thanks.