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

[Jerin Jacob <jerinjacobk@gmail.com>]

On Mon, Jun 30, 2025 at 4:47 PM Mattias Rönnblom <hofors@lysator.liu.se> wrote:
>
> 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.

How is it in Intel PMD?

>
> 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.

Agree. or make it a power save mode or so.

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