-----邮件原件-----
发件人: Pavan Nikhilesh Bhagavatula [off-list ref]
发送时间: 2021年1月5日 18:09
收件人: Feifei Wang [off-list ref]; Harry van Haaren
[off-list ref]; Nikhil Rao [off-list ref]; Pavan
Nikhilesh [off-list ref]
抄送: dev@dpdk.org; jerinj@marvell.com; nd [off-list ref];
stable@dpdk.org; Ruifeng Wang [off-list ref]; Honnappa
Nagarahalli [off-list ref]
主题: RE: [EXT] [PATCH v3] examples/eventdev: refactor ethdev port stop

Hi, Pavan

Hi Feifei,

quoted

Move eth stop code from "signal_handler" function to the end of "main"
function. There are two reasons for this:

First, this improves code maintenance and makes code look simple and
clear. Based on this change, after receiving the interrupt signal,
"fdata->done" is set as 1. Then the main thread will wait all worker
lcores to jump out of the loop. Finally, the main thread will stop and
then close eth dev port.

Second, for older version, the main thread first stops eth dev port and
then waits the end of worker lcore. This may cause errors because it
may stop the eth dev port which worker lcores are using. This moving
change can fix this by waiting all worker threads to exit and then stop
the eth dev port.

Apologies for the delayed reply,

In case of event dev the workers don't interact with eth device directly,
Instead eth device "injects" packets into event device and event device is
responsible for scheduling them to the workers.

If the producer is not stopped i.e. in this case eth device then the worker
threads might never exit and the main core would wait indefinitely for
workers to exit. This will be predominantly seen in cases where there are
only a few flows and large number of workers causing a lot of intra thread
dependency.

For the case that the event device scheduling packets to the workers. Though the producer
is not stopped (eth device), when the main core receive the interrupt signal, the "fdata->done"
will be set as 1. Then all the workers load the value 1 of "fdata->done" and jump out of the loop
to finish their thread.

Best Regards
Feifei

Regards,
Pavan.

quoted

In the meanwhile, remove wmb in signal_handler.

This is because when the main lcore receive the stop signal, it stores
1 into fdata->done. And then the worker lcores load "fdata->done" and
jump out of the loop to stop running. Nothing should be stored after
updating
fdata->done, so the wmb is unnecessary.

Fixes: 085edac2ca38 ("examples/eventdev_pipeline: support Tx
adapter")
Cc: pbhagavatula@marvell.com
Cc: stable@dpdk.org

Suggested-by: Ruifeng Wang <redacted>
Signed-off-by: Feifei Wang <redacted>
Reviewed-by: Ruifeng Wang <redacted>
Reviewed-by: Honnappa Nagarahalli
[off-list ref]
Acked-by: Harry van Haaren <redacted>
---

v2:
1. Delete unused variable to fix build error 2. Reduce commit message
length to fix coding style issues

v3:
1. Title improvement (Van Haaren)

examples/eventdev_pipeline/main.c | 16 ++++------------
1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/examples/eventdev_pipeline/main.c

b/examples/eventdev_pipeline/main.c
index 823f8b51c..fdbaf667b 100644

--- a/examples/eventdev_pipeline/main.c
+++ b/examples/eventdev_pipeline/main.c

@@ -280,7 +280,6 @@ static void

signal_handler(int signum)
{
	static uint8_t once;
-	uint16_t portid;

	if (fdata->done)
		rte_exit(1, "Exiting on signal %d\n", signum); @@ -291,17

+290,6 @@

quoted

signal_handler(int signum)
			rte_event_dev_dump(0, stdout);
		once = 1;
		fdata->done = 1;
-		rte_smp_wmb();
-
-		RTE_ETH_FOREACH_DEV(portid) {
-			rte_event_eth_rx_adapter_stop(portid);
-			rte_event_eth_tx_adapter_stop(portid);
-			if (rte_eth_dev_stop(portid) < 0)
-				printf("Failed to stop port %u", portid);
-		}
-
-		rte_eal_mp_wait_lcore();
-
	}
	if (signum == SIGTSTP)
		rte_event_dev_dump(0, stdout);

@@ -465,6 +453,10 @@ main(int argc, char **argv)

	}

	RTE_ETH_FOREACH_DEV(portid) {
+		rte_event_eth_rx_adapter_stop(portid);
+		rte_event_eth_tx_adapter_stop(portid);
+		if (rte_eth_dev_stop(portid) < 0)
+			printf("Failed to stop port %u", portid);
		rte_eth_dev_close(portid);
	}

--
2.25.1