From: John Fastabend <john.r.fastabend@intel.com>
To: David Miller <davem@davemloft.net>,
"Kirsher, Jeffrey T" <jeffrey.t.kirsher@intel.com>
Cc: therbert@google.com, alexander.duyck@gmail.com,
alexander.h.duyck@intel.com, jeffrey.t.kirsher@intel.com,
netdev@vger.kernel.org, gospo@redhat.com, sassmann@redhat.com
Subject: Re: [net-next 04/14] net: Fix issue with netdev_tx_reset_queue not resetting queue from XOFF state
Date: Sun, 22 Apr 2012 20:21:17 -0700 [thread overview]
Message-ID: <4F94CAAD.1040207@intel.com> (raw)
In-Reply-To: <20120421.161842.1097392704709233196.davem@davemloft.net>
On 4/21/2012 1:18 PM, David Miller wrote:
> From: John Fastabend <john.r.fastabend@intel.com>
> Date: Sat, 21 Apr 2012 09:27:31 -0700
>
>> On 4/20/2012 11:01 PM, Tom Herbert wrote:
>>>> I don't recall the exact reason now, as John said I think it had to do
>>>> with the ethtool tests not using the same cleanup routine and leaving
>>>> us in a bad state. I am pretty sure there was some path in which
>>>> where the call was didn't work but I do not recall the exact details
>>>> now. Most of the reason for moving it is due to the fact that the
>>>> reset is now also clearing the bit, and from the driver perspective we
>>>> didn't need it in two places. After looking it all over again, I
>>>> suppose this causes a cosmetic issue for the bql "inflight" statistic
>>>> in sysfs since the value will be retained until the interface is
>>>> brought back up with this change. Is that an issue or something that
>>>> can be lived with since the interface isn't active anyway in this
>>>> case?
>>>>
>>> On the surface, it seems cleaner and probably a simpler convention to
>>> clear the state when the buffers are being freed. If there's a good
>>> reason not to do this for igb, it makes me wonder if this should be
>>> done the same way in other drivers...
>>>
>>> Tom
>>
>> Just dug up the old thread. This was to fix a bug that byte queue limits
>> was causing with some of the loopback tests evoked from ethtool. The
>> loopback test uses a separate path to free the buffers which wasn't
>> calling netdev_tx_reset_queue().
>>
>> We should likely just explicitly clear the state in each routine rather
>> than try to be clever IMO.
>
> Agreed.
Further it can cause a real bug (the qdisc stack bit doesn't get cleared) if
the real_num_tx_queues is decreased for example in ixgbe when DCB is disabled.
I'll send a patch to JeffK.
Thanks,
John
next prev parent reply other threads:[~2012-04-23 3:21 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-13 4:03 [net-next 00/14][pull request] Intel Wired LAN Driver Updates Jeff Kirsher
2012-03-13 4:03 ` [net-next 01/14] igb: fix ethtool offline test Jeff Kirsher
2012-03-13 4:03 ` [net-next 02/14] ixgbe: remove tie between NAPI work limits and interrupt moderation Jeff Kirsher
2012-03-13 4:03 ` [net-next 03/14] ixgbe: add support for byte queue limits Jeff Kirsher
2012-03-13 4:03 ` [net-next 04/14] net: Fix issue with netdev_tx_reset_queue not resetting queue from XOFF state Jeff Kirsher
2012-04-20 21:19 ` Tom Herbert
2012-04-20 21:31 ` John Fastabend
2012-04-21 3:24 ` Alexander Duyck
2012-04-21 6:01 ` Tom Herbert
2012-04-21 16:27 ` John Fastabend
2012-04-21 20:18 ` David Miller
2012-04-23 3:21 ` John Fastabend [this message]
2012-03-13 4:03 ` [net-next 05/14] net: Add memory barriers to prevent possible race in byte queue limits Jeff Kirsher
2012-03-13 4:03 ` [net-next 06/14] ixgbe: Do no clear Tx status bits since eop_desc provides enough info Jeff Kirsher
2012-03-13 4:03 ` [net-next 07/14] ixgbe: Reorder adapter contents for better cache utilization Jeff Kirsher
2012-03-13 4:03 ` [net-next 08/14] ixgbe: Address issues with Tx WHTRESH value not being set correctly Jeff Kirsher
2012-03-13 4:03 ` [net-next 09/14] ixgbe: Correct Adaptive Interrupt Moderation so that it will change values Jeff Kirsher
2012-03-13 4:03 ` [net-next 10/14] ixgbe: Default to queue pairs when number of queues is less than CPUs Jeff Kirsher
2012-03-13 4:03 ` [net-next 11/14] ixgbe: Drop unnecessary napi_schedule_prep and spare blank line from ixgbe_intr Jeff Kirsher
2012-03-13 4:03 ` [net-next 12/14] ixgbe: Allocate rings as part of the q_vector Jeff Kirsher
2012-03-13 4:03 ` [net-next 13/14] ixgbe: Add iterator for cycling through rings on a q_vector Jeff Kirsher
2012-03-13 4:03 ` [net-next 14/14] ixgbe: Simplify logic for ethtool loopback frame creation and testing Jeff Kirsher
2012-03-13 5:55 ` [net-next 00/14][pull request] Intel Wired LAN Driver Updates David Miller
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