netdev - Re: [PATCH v2 1/1] drivers core: multi-threading device shutdown

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Date:   Wed, 23 May 2018 12:40:29 +0200
From:   Pavel Machek <pavel@....cz>
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,
        gregkh@...uxfoundation.org, alexander.duyck@...il.com,
        tobin@...orbit.com
Subject: Re: [PATCH v2 1/1] drivers core: multi-threading device shutdown

Hi!

> When system is rebooted, halted or kexeced device_shutdown() is
> called.
> 
> This function shuts down every single device by calling either:
> 
> 	dev->bus->shutdown(dev)
> 	dev->driver->shutdown(dev)
...
> Finally, with ixgbe_shutdown() it takes 0.37 for each device, but that time
> is spread all over the place, with bigger offenders:
> 
>     ixgbe_shutdown
>       __ixgbe_shutdown
>         ixgbe_close_suspend
>           ixgbe_down
>             ixgbe_init_hw_generic
>               ixgbe_reset_hw_X540
>                 msleep(100);                        0.104483472
>                 ixgbe_get_san_mac_addr_generic      0.048414851
>                 ixgbe_get_wwn_prefix_generic        0.048409893
>               ixgbe_start_hw_X540
>                 ixgbe_start_hw_generic
>                   ixgbe_clear_hw_cntrs_generic      0.048581502
>                   ixgbe_setup_fc_generic            0.024225800

ixgbe is network card, right? So ... it does not have any persistent
state and no moving parts, and there's no reason we could not "just
power it down"?
>  /*

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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