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From: Gabor LENCSE <lencse@hit.bme.hu>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: users@dpdk.org
Subject: Re: rte_exit() does not terminate the program -- is it a bug or a new feature?
Date: Mon, 18 Sep 2023 20:23:25 +0200	[thread overview]
Message-ID: <9d41e20b-f0b9-eba0-484c-8bafc96c5ca9@hit.bme.hu> (raw)
In-Reply-To: <20230917142753.596c988a@hermes.local>

Dear Stephen,

Thank you very much for your reply. Please see my answers inline.

On 9/17/2023 11:27 PM, Stephen Hemminger wrote:
> On Sun, 17 Sep 2023 21:37:30 +0200
> Gabor LENCSE <lencse@hit.bme.hu> wrote:
>> However, l2fwd also uses the "rte_exit()" function to terminate the
>> program. The only difference is that it calls the "rte_exit()" function
>> from the main program, and I do so in a thread started by the
>> "rte_eal_remote_launch()" function.
> Calling rte_exit in a thread other than main thread won't work because
> the cleanup code is calling rte_eal_cleanup, and inside that it ends
> up waiting for all workers.  Since the thread you are calling from
> is a worker, it ends up waiting for itself.
> rte_exit()
> 	rte_eal_cleanup()
> 		rte_service_finalize()
> 			rte_eal_mp_wait_lcore()
> void
> rte_eal_mp_wait_lcore(void)
> {
> 	unsigned lcore_id;
> 		rte_eal_wait_lcore(lcore_id);
> 	}
> }

Thank you very much for the detailed explanation!

I have modified the send function of siitperf (just at one point as a 
quick hack) and also the bash shell script. Now it works well and 
produces meaningful self-test results without any problem with program 
termination. So, the issue is solved. :-)

Of course, I will review all my rte_exit calls... It'll take a while...

I am just curious, as I have no idea, why my old code worked all right 
with DPDK 16.11. Has rte_exit() been changed since then?

(But, please do not spend too much time with this question!)

> Either service handling needs to be smarter, the rte_exit() function
> check if it is called from main lcore, and/or documentation needs update.
> Not a simple fix because in order to safely do the cleanup logic
> all threads have to gone to a quiescent state.

Yes I think it definitely SHOULD be mentioned in DPDK documentation that 
the rte_exit() function may be called only from the main lcore.

Now I have learnt it for all my life, but it will be useful for a lot of 
DPDK users. :-)

Once again, thank you very much for your help!

Best regards,


p.s.: I have another, even worse problem with siitperf running with the 
new versions of DPDK. I will report it with a different subject line.


  reply	other threads:[~2023-09-18 18:23 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-15  8:24 Gabor LENCSE
2023-09-15 15:06 ` Stephen Hemminger
2023-09-15 18:28   ` Gabor LENCSE
2023-09-15 21:33     ` Stephen Hemminger
2023-09-17 19:37       ` Gabor LENCSE
2023-09-17 21:27         ` Stephen Hemminger
2023-09-18 18:23           ` Gabor LENCSE [this message]
2023-09-18 18:49             ` Stephen Hemminger

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