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From: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
To: Stephen Hemminger <stephen@networkplumber.org>,
	Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
Cc: "Van Haaren, Harry" <harry.van.haaren@intel.com>,
	dpdk-dev <dev@dpdk.org>,
	 Tomasz Piatkowski <tomasz.piatkowski@ericsson.com>,
	nd <nd@arm.com>
Subject: Re: [dpdk-dev] Retrieving lcore worker thread id
Date: Wed, 15 Jul 2020 10:17:09 +0000
Message-ID: <973a2a40-4ff2-96b8-c5e0-17992c40b5d8@ericsson.com> (raw)
In-Reply-To: <20200714135138.136f2a56@hermes.lan>

On 2020-07-14 22:51, Stephen Hemminger wrote:
> On Tue, 14 Jul 2020 18:59:59 +0000
> Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com> wrote:
>> <snip>
>>>> Hi.
>>> Hey,
>>>> In DPDK 19.11, the lcore_config struct of <rte_lcore.h> is made
>>>> private, and with it the possibility to look up the thread id of the
>>>> lcore worker threads disappears.
>>>> One use case is an application with a monitoring function (on some
>>>> control plane thread), which uses the thread ids to make sure the
>>>> worker threads gets the CPU runtime they should, and thus is able to
>>>> detect stalls.
>> This sounds similar to 'keep alive' functionality.
>>>> Is there some other way of finding out the thread_id of a lcore worker
>>>> thread? All I can think of are hacks like using a temporary service
>>>> function for service cores, in combination with requiring launched
>>>> application threads also to store their thread id in some global
>>>> structure (index by lcore_id).
>>> -1 for the service cores idea. I like the creative solution thinking, but not as a
>>> long-term solution.
>>>> Is there some cleaner way? If not, would adding something like a
>>>> rte_lcore_thread_id() function make sense?
>> I guess here you mean the OS provided thread ID. Are there OS calls that provide the CPU runtime?
> This might be difficult sinc thread id in Linux/glibc is intentionally and opaque value.
> According to Posix the only valid way to look at it is to use return value from
> pthread_create() and pthread_self().

The rte_lcore_thread_id() would return this value, which could 
subsequently be used in the application, calling pthread_getcpuclockid() 
and clock_gettime() to retrieve the run time for the lcore worker 
thread. No need to break the opacity in this case, although the Linux 
thread id (i.e. the result of a gettid()) would be useful in case you 
would want to dig around in /proc for other scheduler statistics.



  reply	other threads:[~2020-07-15 10:17 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-14 12:03 Mattias Rönnblom
2020-07-14 13:08 ` Van Haaren, Harry
2020-07-14 18:59   ` Honnappa Nagarahalli
2020-07-14 20:51     ` Stephen Hemminger
2020-07-15 10:17       ` Mattias Rönnblom [this message]
2020-07-15 16:21         ` Stephen Hemminger
2020-07-16 10:20           ` Mattias Rönnblom
2020-08-10  9:36             ` [dpdk-dev] [RFC] eal: introduce function to get lcore " Mattias Rönnblom
2020-10-20 13:38               ` David Marchand
2020-10-20 18:40                 ` Mattias Rönnblom
2020-07-15 10:21   ` [dpdk-dev] Retrieving lcore worker " Mattias Rönnblom

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