Re: [SPDK] "Requested device XXX cannot be used" warning in device detach procedure may be misleading

Re: [SPDK] "Requested device XXX cannot be used" warning in device detach procedure may be misleading

[Walker, Benjamin]

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On Mon, 2017-03-13 at 12:28 +0800, Freeman Zhang wrote:
> Hi
> 
> On 3/13/17 12:03 PM, Chang, Cunyin wrote:
> > 
> > Actually, the error message caused by the function
> > spdk_pci_device_detach(), after we detach the device, we try to
> > call the function
> > rte_eal_pci_probe_one(), but we do not have callback function for
> > the dpdk nvme driver at this point, so the error message show up, 
> > but  this function will add the device back to dpdk pci device
> > list, then we could probe the device next time when
> > we want to use it again. So it has no adverse effects but just one
> > error message, but we still trying to fix it now.
> > 
> 
> Thanks for your reply!
> 
> I've noticed it and that is why I think it's kind of misleading. So I
> guess we should not focus only on reusing codes but also making it
> clearer for both users and developers.

The problem is that DPDK is not exposing a public API to do the
operation we need to do (unload a driver but not remove it entirely
from the list of PCI devices). We're working with the DPDK team to add
a public API to do that while also investigating better ways to work
around the issue that don't leave us with this confusing error message.

> 
> 
> All the best!
> Freeman
> 
> _______________________________________________
> SPDK mailing list
> SPDK(a)lists.01.org
> https://lists.01.org/mailman/listinfo/spdk

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Re: [SPDK] "Requested device XXX cannot be used" warning in device detach procedure may be misleading

[Freeman Zhang]

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Hi

On 3/13/17 12:03 PM, Chang, Cunyin wrote:
> 
> Actually, the error message caused by the function spdk_pci_device_detach(), after we detach the device, we try to call the function
> rte_eal_pci_probe_one(), but we do not have callback function for the dpdk nvme driver at this point, so the error message show up, 
> but  this function will add the device back to dpdk pci device list, then we could probe the device next time when
> we want to use it again. So it has no adverse effects but just one error message, but we still trying to fix it now.
> 

Thanks for your reply!

I've noticed it and that is why I think it's kind of misleading. So I
guess we should not focus only on reusing codes but also making it
clearer for both users and developers.


All the best!
Freeman


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Re: [SPDK] "Requested device XXX cannot be used" warning in device detach procedure may be misleading

[Chang, Cunyin]

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Hi Freeman,

Actually, the error message caused by the function spdk_pci_device_detach(), after we detach the device, we try to call the function
rte_eal_pci_probe_one(), but we do not have callback function for the dpdk nvme driver at this point, so the error message show up, 
but  this function will add the device back to dpdk pci device list, then we could probe the device next time when
we want to use it again. So it has no adverse effects but just one error message, but we still trying to fix it now.

Thanks,
Cunyin

-----Original Message-----
From: SPDK [mailto:spdk-bounces(a)lists.01.org] On Behalf Of Freeman Zhang
Sent: Sunday, March 12, 2017 11:44 AM
To: spdk(a)lists.01.org
Subject: [SPDK] "Requested device XXX cannot be used" warning in device detach procedure may be misleading

Hi list!

I am a new user to spdk, I trapped in some confusing warnings recently.
This one is about "Requested device XXX cannot be used" printed at the end of spdk/example/nvm/perf/perf execution. That seems to tell me: hey, your device doesn't work with spdk... yes, even though you've got the perf results, but you'd better not trust it!

After investigating the source code, I understand the last print of this warning appears when spdk releases resources after all work is done. So I suppose it should say something like "we are finishing using this device" instead. What do you think?

I also put this on github issues page
(https://github.com/spdk/spdk/issues/127), but still think I can collect more ideas from the mailing list.


All the best!
Freeman

[SPDK] "Requested device XXX cannot be used" warning in device detach procedure may be misleading

[Freeman Zhang]

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Hi list!

I am a new user to spdk, I trapped in some confusing warnings recently.
This one is about "Requested device XXX cannot be used" printed at the
end of spdk/example/nvm/perf/perf execution. That seems to tell me: hey,
your device doesn't work with spdk... yes, even though you've got the
perf results, but you'd better not trust it!

After investigating the source code, I understand the last print of this
warning appears when spdk releases resources after all work is done. So
I suppose it should say something like "we are finishing using this
device" instead. What do you think?

I also put this on github issues page
(https://github.com/spdk/spdk/issues/127), but still think I can collect
more ideas from the mailing list.


All the best!
Freeman


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