[dpdk-dev] [PATCH v6 0/4] support reset of VF link

Luca Boccassi lboccass at Brocade.com
Thu Jul 7 12:20:51 CEST 2016


On Thu, 2016-07-07 at 01:09 +0000, Lu, Wenzhuo wrote:
> Hi Luca,
> 
> 
> > -----Original Message-----
> > From: Luca Boccassi [mailto:lboccass at Brocade.com]
> > Sent: Thursday, July 7, 2016 12:23 AM
> > To: Lu, Wenzhuo
> > Cc: dev at dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH v6 0/4] support reset of VF link
> > 
> > On Wed, 2016-07-06 at 00:45 +0000, Lu, Wenzhuo wrote:
> > > Hi Luca,
> > >
> > > > -----Original Message-----
> > > > From: Luca Boccassi [mailto:lboccass at Brocade.com]
> > > > Sent: Tuesday, July 5, 2016 5:53 PM
> > > > To: Lu, Wenzhuo
> > > > Cc: dev at dpdk.org
> > > > Subject: Re: [dpdk-dev] [PATCH v6 0/4] support reset of VF link
> > > >
> > > > On Tue, 2016-07-05 at 00:52 +0000, Lu, Wenzhuo wrote:
> > > > > Hi Luca,
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Luca Boccassi [mailto:lboccass at Brocade.com]
> > > > > > Sent: Monday, July 4, 2016 11:48 PM
> > > > > > To: Lu, Wenzhuo
> > > > > > Cc: dev at dpdk.org
> > > > > > Subject: Re: [dpdk-dev] [PATCH v6 0/4] support reset of VF link
> > > > > >
> > > > > > On Mon, 2016-06-20 at 14:24 +0800, Wenzhuo Lu wrote:
> > > > > > > If the PF link is down and up, VF link will not work accordingly.
> > > > > > > This patch set addes the support of VF link reset. So, when VF
> > > > > > > receices the messges of physical link down/up. APP can reset
> > > > > > > the VF link and let it recover.
> > > > > > >
> > > > > > > PS: This patch set is splitted from a previous patch set,
> > > > > > > *automatic link recovery on ixgbe/igb VF*, and it's base on
> > > > > > > the patch set *support mailbox interruption on ixgbe/igb VF*.
> > > > > > >
> > > > > > > Wenzhuo Lu (3):
> > > > > > >   lib/librte_ether: support device reset
> > > > > > >   ixgbe: implement device reset on VF
> > > > > > >   igb: implement device reset on VF
> > > > > > >
> > > > > > > Zhe Tao (1):
> > > > > > >   i40e: implement device reset on VF
> > > > > > >
> > > > > > > v1:
> > > > > > > - Added the implementation for the VF reset functionality.
> > > > > > > v2:
> > > > > > > - Changed the i40e related operations during VF reset.
> > > > > > > v3:
> > > > > > > - Resent the patches because of the mail sent issue.
> > > > > > > v4:
> > > > > > > - Removed some VF reset emulation code.
> > > > > > > v5:
> > > > > > > - Removed all the code related with lock.
> > > > > > > v6:
> > > > > > > - Updated the NIC feature overview matrix.
> > > > > > > - Added more explanation in the doxygen comment of reset API.
> > > > > > >
> > > > > > >  doc/guides/nics/overview.rst           |  1 +
> > > > > > >  doc/guides/rel_notes/release_16_07.rst | 13 ++++++
> > > > > > >  drivers/net/e1000/igb_ethdev.c         | 59 ++++++++++++++++++++++++
> > > > > > >  drivers/net/i40e/i40e_ethdev.h         |  4 ++
> > > > > > >  drivers/net/i40e/i40e_ethdev_vf.c      | 83
> > > > > > ++++++++++++++++++++++++++++++++++
> > > > > > >  drivers/net/i40e/i40e_rxtx.c           | 10 ++++
> > > > > > >  drivers/net/i40e/i40e_rxtx.h           |  4 ++
> > > > > > >  drivers/net/ixgbe/ixgbe_ethdev.c       | 64
> > +++++++++++++++++++++++++-
> > > > > > >  drivers/net/ixgbe/ixgbe_ethdev.h       |  2 +-
> > > > > > >  drivers/net/ixgbe/ixgbe_rxtx.c         | 12 +++--
> > > > > > >  lib/librte_ether/rte_ethdev.c          | 17 +++++++
> > > > > > >  lib/librte_ether/rte_ethdev.h          | 24 ++++++++++
> > > > > > >  lib/librte_ether/rte_ether_version.map |  7 +++
> > > > > > >  13 files changed, 295 insertions(+), 5 deletions(-)
> > > > > >
> > > > > > Hello Wenzhuo,
> > > > > >
> > > > > > I'm testing this patchset, but I am sporadically running into an
> > > > > > issue where the VFs reset fails after the PF flaps.
> > > > > >
> > > > > > I have a VM running on a KVM box with a X540-AT2, passing 2 VFs in.
> > > > > >
> > > > > > I am using calling rte_eth_dev_reset in response to a
> > > > > > RTE_ETH_EVENT_INTR_RESET callback, and the following errors
> > > > > > appear in the
> > > > > > log:
> > > > > >
> > > > > > PMD: ixgbevf_dev_reset(): Ixgbe VF reset: Failed to update link.
> > > > > > PMD: ixgbe_alloc_rx_queue_mbufs(): RX mbuf alloc failed
> > > > > > queue_id=0
> > > > > > PMD: ixgbevf_dev_start(): Unable to initialize RX hardware (-12)
> > > > > > PMD: ixgbevf_dev_reset(): Ixgbe VF reset: Failed to start device.
> > > > > >
> > > > > > Jumping in with GDB, it seems that the rte_rxmbuf_alloc call in
> > > > > > ixgbe_alloc_rx_queue_mbufs returns NULL at iteration 64 out of 2048.
> > > > > > The application has ~500 2MB hugepages, and there's 2GB of free
> > > > > > memory available on top of that.
> > > > > >
> > > > > > Have you seen this before? Any pointer or suggestion for debugging?
> > > > > >
> > > > > > Thanks!
> > > > > >
> > > > > > --
> > > > > > Kind regards,
> > > > > > Luca Boccassi
> > > > > I think the problem is the mbuf occupied by the packets is not
> > > > > released. This
> > > > memory has to be released by the APP, so my patches haven’t covered this.
> > > > Actually an example is needed to show how to use the reset API. I
> > > > plan to modify the testpmd.
> > > > > You may notice this feature is postponed to 16.11. Would you like
> > > > > to wait for
> > > > the new version that will include an example?
> > > >
> > > > Hi,
> > > >
> > > > Unfortunately we need the VF reset working sooner than that, so one
> > > > way or the other I'll need to sort it out. Given I've got a use case
> > > > where this is happening, if it can be helpful for you I'm more than
> > > > happy to help as a guinea pig. If you could please give some
> > > > guidance/guidelines with regards to which API to use to sort the mbuf
> > problem, I can try it out and give back some feedback.
> > > >
> > > > Thanks!
> > > I made a stupid mistake and deleted all my code. So, I have to take
> > > some time to rewrite it :( Attached the example I used to test the reset API. It's
> > modified from the l2fwd example. So you can compare it with l2fwd to see what
> > need to be added.
> > > Hopefully it can help :)
> > 
> > Thanks! That made me understand a couple of things more, and I've got past the
> > problem.
> > 
> > Unfortunately now there's a bigger issue - rte_eth_dev_reset is a blocking call.
> > the _RESET event callback is fired when the PF goes down, but when I call
> > rte_eth_dev_reset it will block until the PF goes back up. There is no way, as far
> > as I can see, to know if the PF is back up before calling rte_eth_dev_reset.
> > 
> > This is a problem because, as far as I understand, I have to call all the
> > rte_eth_dev_ APIs from the same thread, in my case the master thread, and I
> > can't have that block potentially indefinitely.
> > 
> > Would it be possible to have 2 events instead of 1, one when the PF goes down
> > and one when it goes up? This way an application would be able to soft-stop the
> > port (drain queues, etc) when the PF is down, and then call the reset API when it
> > goes back up.
> > 
> > Thanks!
> Sorry we cannot have 2 events now. There're 2 problems to have 2 events.
> 1, Normally we use kernel driver for PF. Now the kernel driver only have one kind of message for link down and up. So we cannot tell if it's down or up.
> 2, When the PF is down, if we don't reset the VF, VF is not working. It cannot receive any message from PF. So we cannot know that when PF is up. It means normally we have to reset VF twice when PF down and up. (Surely we can wait a while when we receive the message from PF until PF is up. But we cannot tell how long the time is appropriate. So this *wait a while* may work for flash.)

Thanks for the clarification, I understand.

The problem with a blocking call is that we basically need to spawn one
thread per rte_eth_dev_reset call, since there is no way of knowing if a
PF is down for good or just flapping, and we can't have a single thread
managing all the interfaces being blocked forever (EG: PF 1 and 2 go
down, thread blocks on PF 1 reset call but it never returns, meanwhile
PF 2 goes back up but call is never made).

A colleague of mine, Eric Kinzie, suggested to add a blocking boolean
parameter to rte_eth_dev_reset API. If set to false, then the call will
not block and just does one try and return an error (EAGAIN ?). Would
this be an acceptable proposition?

-- 
Kind regards,
Luca Boccassi


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