On 2025-06-30 18:18, Pathak, Pravin wrote:
-----Original Message-----
From: Jerin Jacob <jerinjac...@gmail.com>
Sent: Monday, June 30, 2025 7:44 AM
To: Mattias Rönnblom <hof...@lysator.liu.se>
Cc: Pathak, Pravin <pravin.pat...@intel.com>; dev@dpdk.org;
jer...@marvell.com; Chen, Mike Ximing <mike.ximing.c...@intel.com>;
Richardson, Bruce <bruce.richard...@intel.com>; tho...@monjalon.net;
Marchand, David <david.march...@redhat.com>; nipun.gu...@amd.com;
chen...@nvidia.com; Sarkar, Tirthendu <tirthendu.sar...@intel.com>; Pavan
Nikhilesh <pbhagavat...@marvell.com>; Shijith Thotton
<sthot...@marvell.com>; Hemant Agrawal <hemant.agra...@nxp.com>;
Sachin Saxena <sachin.sax...@oss.nxp.com>; harry.ch...@intel.com;
Mattias Rönnblom <mattias.ronnb...@ericsson.com>
Subject: Re: [PATCH v1] event/dlb2: add dequeue interrupt mode support
On Mon, Jun 30, 2025 at 4:47 PM Mattias Rönnblom <hof...@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.pat...@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.pat...@intel.com>
Signed-off-by: Tirthendu Sarkar <tirthendu.sar...@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?
It would be best if we configure it per port using RTE_EVENT_PORT_CFG_* flags.
Will it be, OK?
The dequeue timeout will be honored, and the decision to block or return will
be made after the timeout.
That doesn't sound like the timeout is honored.
The reason an application wants the dequeue call to complete within a
certain time, even though there wasn't any events, is likely because it
want to go do something else with that thread, after the timeout.
Thus, you can't decide to block the thread *after* the timeout. If you
block, you have to do some time *before* the timeout, and wake up in
time to meet the deadline.
For example, if the event device is given a 1 ms dequeue timeout by the
application, it could go busy-poll for 10 us, then busy-poll with a
short tpause for 100 us, and then put the thread to sleep blocking on
some fd for the remaining 890 us.
The hardware-specific nature of the timing and exact mechanism to use
speaks against having this kind of configuration in the Eventdev API.
If not interrupt, it can be called blocking vs polling mode. If the port
config is fine, I will create a new patch with it.
Also, we should have this as a capability for eventdevs.
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.
