> -----邮件原件-----
> 发件人: Pavan Nikhilesh Bhagavatula <[email protected]>
> 发送时间: 2021年1月5日 18:09
> 收件人: Feifei Wang <[email protected]>; Harry van Haaren
> <[email protected]>; Nikhil Rao <[email protected]>; Pavan
> Nikhilesh <[email protected]>
> 抄送: [email protected]; [email protected]; nd <[email protected]>;
> [email protected]; Ruifeng Wang <[email protected]>; Honnappa
> Nagarahalli <[email protected]>
> 主题: RE: [EXT] [PATCH v3] examples/eventdev: refactor ethdev port stop
>
Hi, Pavan
> Hi Feifei,
>
> >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.
>
> >
> >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: [email protected]
> >Cc: [email protected]
> >
> >Suggested-by: Ruifeng Wang <[email protected]>
> >Signed-off-by: Feifei Wang <[email protected]>
> >Reviewed-by: Ruifeng Wang <[email protected]>
> >Reviewed-by: Honnappa Nagarahalli
> ><[email protected]>
> >Acked-by: Harry van Haaren <[email protected]>
> >---
> >
> >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 @@
> >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
