netdev - Re: [PATCH v3 0/1] multi-threading device shutdown

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Message-ID: <20180514150336.GA18769@kroah.com>
Date:   Mon, 14 May 2018 17:03:36 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Pavel Tatashin <pasha.tatashin@...cle.com>
Cc:     steven.sistare@...cle.com, daniel.m.jordan@...cle.com,
        linux-kernel@...r.kernel.org, jeffrey.t.kirsher@...el.com,
        intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        alexander.duyck@...il.com, tobin@...orbit.com
Subject: Re: [PATCH v3 0/1] multi-threading device shutdown

On Mon, May 07, 2018 at 11:54:01AM -0400, Pavel Tatashin wrote:
> Changelog
> v2 - v3
> 	- Fixed warning from kbuild test.
> 	- Moved device_lock/device_unlock inside device_shutdown_tree().
> 
> v1 - v2
> 	- It turns out we cannot lock more than MAX_LOCK_DEPTH by a single
> 	  thread. (By default this value is 48), and is used to detect
> 	  deadlocks. So, I re-wrote the code to only lock one devices per
> 	  thread instead of pre-locking all devices by the main thread.
> 	- Addressed comments from Tobin C. Harding.
> 	- As suggested by Alexander Duyck removed ixgbe changes. It can be
> 	  done as a separate work scaling RTNL mutex.
> 
> Do a faster shutdown by calling dev->*->shutdown(dev) in parallel.
> device_shutdown() calls these functions for every single device but
> only using one thread.
> 
> Since, nothing else is running on the machine by the device_shutdown()
> s called, there is no reason not to utilize all the available CPU
> resources.

Ah, we can hope so.  I bet this is going to break something, so can we
have some way of turning it on/off dynamically for when it does?

thanks,

greg k-h