Re: [PATCH v1] event/dlb2: add dequeue interrupt mode support

["Mattias Rönnblom" <hofors@lysator.liu.se>]

On 2025-06-30 11:19, Jerin Jacob wrote:
> On Sat, Jun 28, 2025 at 11:17 AM Pravin Pathak <pravin.pathak@intel.com> wrote:
>>
>> DLB2 port interrupt is implemented using DPDK interrupt
>> framework. This allows eventdev dequeue API to sleep when
>> the port queue is empty and gets wakeup when event arrives
>> at the port. Port dequeue mode is configured using devargs
>> argument port_dequeue_wait. Supported modes are polling and
>> interrupt. Default mode is polling.
>> This commit also adds code to handle device error interrupts
>> and print alarm details.
>>
>> Signed-off-by: Pravin Pathak <pravin.pathak@intel.com>
>> Signed-off-by: Tirthendu Sarkar <tirthendu.sarkar@intel.com>
>> ---
>>   doc/guides/eventdevs/dlb2.rst              |  20 +
>>   drivers/event/dlb2/dlb2.c                  | 236 +++++-
>>   drivers/event/dlb2/dlb2_iface.c            |   7 +
>>   drivers/event/dlb2/dlb2_iface.h            |   8 +
>>   drivers/event/dlb2/dlb2_priv.h             |  18 +
>>   drivers/event/dlb2/dlb2_user.h             | 112 +++
>>   drivers/event/dlb2/pf/base/dlb2_hw_types.h |  70 ++
>>   drivers/event/dlb2/pf/base/dlb2_osdep.h    |  46 ++
>>   drivers/event/dlb2/pf/base/dlb2_regs.h     | 149 +++-
>>   drivers/event/dlb2/pf/base/dlb2_resource.c | 825 +++++++++++++++++++++
>>   drivers/event/dlb2/pf/base/dlb2_resource.h |   6 +
>>   drivers/event/dlb2/pf/dlb2_pf.c            | 223 ++++++
>>   12 files changed, 1711 insertions(+), 9 deletions(-)
>>
>> diff --git a/doc/guides/eventdevs/dlb2.rst b/doc/guides/eventdevs/dlb2.rst
>> index 8ec7168f20..a4ba857351 100644
>> --- a/doc/guides/eventdevs/dlb2.rst
>> +++ b/doc/guides/eventdevs/dlb2.rst
>> @@ -477,6 +477,26 @@ Example command to use as meson option for credit handling:
>>
>>          meson configure -Dc_args='-DDLB_SW_CREDITS_CHECKS=0 -DDLB_HW_CREDITS_CHECKS=1'
>>
>> +Interrupt Mode Support
>> +~~~~~~~~~~~~~~~~~~~~~~
>> +DLB dequeue supports interrupt mode for the API rte_event_dequeue_burst().
>> +The default port dequeue mode is polling. Dequeue wait mode can be configured
>> +on per eventdev port basis using devargs argument 'port_dequeue_wait'. In
>> +interrupt mode, if the port queue is empty, the application thread will block
>> +on the interrupt until a new event arrives. It enters blocking mode only after
>> +any specified timeout. During the timeout, it will poll the port queue for
>> +events as usual. Interrupt mode uses the DPDK interrupt support framework.
>> +
>> +    .. code-block:: console
>> +
>> +       --allow ea:00.0,port_dequeue_wait=all:interrupt
> 
> Adding other eventdev PMD mainatainers.
> 
> Looks like it can be a generic feature. i.e set this option is dev_configure()
> If there is no objection, Please send a new patch around that.

I've considered implementing this in DSW, although in a different manner 
(with eventfds and poll()).

The dequeue timeout will still be honored in "interrupt mode", correct? 
It wasn't obvious from the description.

What's being configured should just be a threshold time at which the 
event device would go from busy-polling to blocking the thread.

Maybe it should be called something with "blocking" or "sleeping", 
instead of "interrupt", since interrupts are never directly involved.

Anyway, seems like a good candidate for a generic feature to me.