[dpdk-users] QAT PMD in multi-process mode

[dpdk-users] QAT PMD in multi-process mode

[Pathak, Pravin]

Hi -
In multi-process model, if same QAT VF is shared between two processes which are spawned from separate executables,  primary process give segfault while accessing QAT functions.
It looks like PMD installs access functions in shared area so when secondary process changes those function pointers, they are no longer valid in primary process.

Is QAT PMD going to modified to support this mode in future?
Regards
Pravin

Re: [dpdk-users] QAT PMD in multi-process mode

[Trahe, Fiona]

Hi Pravin,

> -----Original Message-----
> From: users <users-bounces@dpdk.org> On Behalf Of Pathak, Pravin
> Sent: Thursday, October 24, 2019 5:12 PM
> To: users@dpdk.org
> Subject: [dpdk-users] QAT PMD in multi-process mode
> 
> Hi -
> In multi-process model, if same QAT VF is shared between two processes which are spawned from
> separate executables,  primary process give segfault while accessing QAT functions.
> It looks like PMD installs access functions in shared area so when secondary process changes those
> function pointers, they are no longer valid in primary process.
>
http://doc.dpdk.org/guides/cryptodevs/qat.html
states
"Each VF can only be used by one DPDK process. It is not possible to share the same VF across multiple processes, even if these processes are using different acceleration services."
However, we are currently investigating use of a QAT VF in a primary and secondary process - but with some constraints about what can be done in each process, e.g. session init in one process and enqueue/dequeue in the other.


> Is QAT PMD going to modified to support this mode in future?
> Regards
> Pravin
> 
> 

Re: [dpdk-users] QAT PMD in multi-process mode

[Pathak, Pravin]

Hi Fiona -
Thanks. We are thinking of usage where  one process only enqueues and other only dequeues over shared VF.
Regards
Pravin

-----Original Message-----
From: Trahe, Fiona 
Sent: Thursday, October 24, 2019 1:03 PM
To: Pathak, Pravin <pravin.pathak@intel.com>; users@dpdk.org
Cc: Trahe, Fiona <fiona.trahe@intel.com>
Subject: RE: QAT PMD in multi-process mode

Hi Pravin,

> -----Original Message-----
> From: users <users-bounces@dpdk.org> On Behalf Of Pathak, Pravin
> Sent: Thursday, October 24, 2019 5:12 PM
> To: users@dpdk.org
> Subject: [dpdk-users] QAT PMD in multi-process mode
> 
> Hi -
> In multi-process model, if same QAT VF is shared between two processes 
> which are spawned from separate executables,  primary process give segfault while accessing QAT functions.
> It looks like PMD installs access functions in shared area so when 
> secondary process changes those function pointers, they are no longer valid in primary process.
>
http://doc.dpdk.org/guides/cryptodevs/qat.html
states
"Each VF can only be used by one DPDK process. It is not possible to share the same VF across multiple processes, even if these processes are using different acceleration services."
However, we are currently investigating use of a QAT VF in a primary and secondary process - but with some constraints about what can be done in each process, e.g. session init in one process and enqueue/dequeue in the other.


> Is QAT PMD going to modified to support this mode in future?
> Regards
> Pravin
> 
>