From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
To: "Tan, Jianfeng" <jianfeng.tan@intel.com>,
Panu Matilainen <pmatilai@redhat.com>,
"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] eal: add option --avail-cores to detect lcores
Date: Wed, 9 Mar 2016 14:44:09 +0000 [thread overview]
Message-ID: <2601191342CEEE43887BDE71AB97725836B1A5A2@irsmsx105.ger.corp.intel.com> (raw)
In-Reply-To: <56E03078.3000501@intel.com>
> -----Original Message-----
> From: Tan, Jianfeng
> Sent: Wednesday, March 09, 2016 2:17 PM
> To: Ananyev, Konstantin; Panu Matilainen; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] eal: add option --avail-cores to detect lcores
>
>
>
> On 3/9/2016 10:01 PM, Ananyev, Konstantin wrote:
> >
> >> -----Original Message-----
> >> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Tan, Jianfeng
> >> Sent: Wednesday, March 09, 2016 1:53 PM
> >> To: Panu Matilainen; dev@dpdk.org
> >> Subject: Re: [dpdk-dev] [PATCH] eal: add option --avail-cores to detect lcores
> >>
> >>
> >>
> >> On 3/9/2016 9:05 PM, Panu Matilainen wrote:
> >>> On 03/08/2016 07:38 PM, Tan, Jianfeng wrote:
> >>>> Hi Panu,
> >>>>
> >>>> On 3/8/2016 4:54 PM, Panu Matilainen wrote:
> >>>>> On 03/04/2016 12:05 PM, Jianfeng Tan wrote:
> >>>>>> This patch adds option, --avail-cores, to use lcores which are
> >>>>>> available
> >>>>>> by calling pthread_getaffinity_np() to narrow down detected cores
> >>>>>> before
> >>>>>> parsing coremask (-c), corelist (-l), and coremap (--lcores).
> >>>>>>
> >>>>>> Test example:
> >>>>>> $ taskset 0xc0000 ./examples/helloworld/build/helloworld \
> >>>>>> --avail-cores -m 1024
> >>>>>>
> >>>>>> Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
> >>>>>> Acked-by: Neil Horman <nhorman@tuxdriver.com>
> >>>>> Hmm, to me this sounds like something that should be done always so
> >>>>> there's no need for an option. Or if there's a chance it might do the
> >>>>> wrong thing in some rare circumstance then perhaps there should be a
> >>>>> disabler option instead?
> >>>> Thanks for comments.
> >>>>
> >>>> Yes, there's a use case that we cannot handle.
> >>>>
> >>>> If we make it as default, DPDK applications may fail to start, when user
> >>>> specifies a core in isolcpus and its parent process (say bash) has a
> >>>> cpuset affinity that excludes isolcpus. Originally, DPDK applications
> >>>> just blindly do pthread_setaffinity_np() and it always succeeds because
> >>>> it always has root privilege to change any cpu affinity.
> >>>>
> >>>> Now, if we do the checking in rte_eal_cpu_init(), those lcores will be
> >>>> flagged as undetected (in my older implementation) and leads to failure.
> >>>> To make it correct, we would always add "taskset mask" (or other ways)
> >>>> before DPDK application cmd lines.
> >>>>
> >>>> How do you think?
> >>> I still think it sounds like something that should be done by default
> >>> and maybe be overridable with some flag, rather than the other way
> >>> around. Another alternative might be detecting the cores always but if
> >>> running as root, override but with a warning.
> >> For your second solution, only root can setaffinity to isolcpus?
> >> Your first solution seems like a promising way for me.
> >>
> >>> But I dont know, just wondering. To look at it from another angle: why
> >>> would somebody use this new --avail-cores option and in what
> >>> situation, if things "just work" otherwise anyway?
> >> For DPDK applications, the most common case to initialize DPDK is like
> >> this: "$dpdk-app [options for DPDK] -- [options for app]", so users need
> >> to specify which cores to run and how much hugepages are used. Suppose
> >> we need this dpdk-app to run in a container, users already give those
> >> information when they build up the cgroup for it to run inside, this
> >> option or this patch is to make DPDK more smart to discover how much
> >> resource will be used. Make sense?
> > But then, all we need might be just a script that would extract this information from the system
> > and form a proper cmdline parameter for DPDK?
>
> Yes, a script will work. Or to construct (argc, argv) to call
> rte_eal_init() in the application. But as Neil Horman once suggested, a
> simple pthread_getaffinity_np() will get all things done. So if it worth
> a patch here?
Don't know...
Personally I would prefer not to put extra logic inside EAL.
For me - there are too many different options already.
From other side looking at the patch itself:
You are updating lcore_count and lcore_config[],based on physical cpu availability,
but these days it is not always one-to-one mapping between EAL lcore and physical cpu.
Shouldn't that be taken into account?
Konstantin
next prev parent reply other threads:[~2016-03-09 14:44 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-24 18:49 [dpdk-dev] [RFC] eal: add cgroup-aware resource self discovery Jianfeng Tan
2016-01-25 13:46 ` Neil Horman
2016-01-26 2:22 ` Tan, Jianfeng
2016-01-26 14:19 ` Neil Horman
2016-01-27 12:02 ` Tan, Jianfeng
2016-01-27 17:30 ` Neil Horman
2016-01-29 11:22 ` [dpdk-dev] [PATCH] eal: make resource initialization more robust Jianfeng Tan
2016-02-01 18:08 ` Neil Horman
2016-02-22 6:08 ` Tan, Jianfeng
2016-02-22 13:18 ` Neil Horman
2016-02-28 21:12 ` Thomas Monjalon
2016-02-29 1:50 ` Tan, Jianfeng
2016-03-04 10:05 ` [dpdk-dev] [PATCH] eal: add option --avail-cores to detect lcores Jianfeng Tan
2016-03-08 8:54 ` Panu Matilainen
2016-03-08 17:38 ` Tan, Jianfeng
2016-03-09 13:05 ` Panu Matilainen
2016-03-09 13:53 ` Tan, Jianfeng
2016-03-09 14:01 ` Ananyev, Konstantin
2016-03-09 14:17 ` Tan, Jianfeng
2016-03-09 14:44 ` Ananyev, Konstantin [this message]
2016-03-09 14:55 ` Tan, Jianfeng
2016-03-09 15:17 ` Ananyev, Konstantin
2016-03-09 17:45 ` Tan, Jianfeng
2016-03-09 19:33 ` Ananyev, Konstantin
2016-03-10 1:36 ` Tan, Jianfeng
2016-05-18 12:46 ` David Marchand
2016-05-19 2:25 ` Tan, Jianfeng
2016-06-30 13:43 ` Thomas Monjalon
2016-07-01 0:52 ` Tan, Jianfeng
2016-04-26 12:39 ` Tan, Jianfeng
2016-03-04 10:58 ` [dpdk-dev] [PATCH] eal: make hugetlb initialization more robust Jianfeng Tan
2016-03-08 1:42 ` [dpdk-dev] [PATCH v2] " Jianfeng Tan
2016-03-08 8:46 ` Tan, Jianfeng
2016-05-04 11:07 ` Sergio Gonzalez Monroy
2016-05-04 11:28 ` Tan, Jianfeng
2016-05-04 12:25 ` Sergio Gonzalez Monroy
2016-05-09 10:48 ` [dpdk-dev] [PATCH v3] " Jianfeng Tan
2016-05-10 8:54 ` Sergio Gonzalez Monroy
2016-05-10 9:11 ` Tan, Jianfeng
2016-05-12 0:44 ` [dpdk-dev] [PATCH v4] " Jianfeng Tan
2016-05-17 16:39 ` David Marchand
2016-05-18 7:56 ` Sergio Gonzalez Monroy
2016-05-18 9:34 ` David Marchand
2016-05-19 2:00 ` Tan, Jianfeng
2016-05-17 16:40 ` Thomas Monjalon
2016-05-18 8:06 ` Sergio Gonzalez Monroy
2016-05-18 9:38 ` David Marchand
2016-05-19 2:11 ` Tan, Jianfeng
2016-05-31 3:37 ` [dpdk-dev] [PATCH v5] eal: fix allocating all free hugepages Jianfeng Tan
2016-06-06 2:49 ` Pei, Yulong
2016-06-08 11:27 ` Sergio Gonzalez Monroy
2016-06-30 13:34 ` Thomas Monjalon
2016-08-31 3:07 ` [dpdk-dev] [PATCH v2] eal: restrict cores detection Jianfeng Tan
2016-08-31 15:30 ` Stephen Hemminger
2016-09-01 1:15 ` Tan, Jianfeng
2016-09-01 1:31 ` [dpdk-dev] [PATCH v3] " Jianfeng Tan
2016-09-02 16:53 ` Bruce Richardson
2016-09-16 14:04 ` Thomas Monjalon
2016-09-16 14:02 ` Thomas Monjalon
2016-12-02 17:48 ` [dpdk-dev] [PATCH v4] eal: restrict cores auto detection Jianfeng Tan
2016-12-08 18:19 ` Thomas Monjalon
2016-12-09 15:14 ` Bruce Richardson
2016-12-21 14:31 ` Thomas Monjalon
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