From: Thomas Monjalon <thomas.monjalon@6wind.com>
To: "Tan, Jianfeng" <jianfeng.tan@intel.com>
Cc: dev@dpdk.org, David Marchand <david.marchand@6wind.com>,
Panu Matilainen <pmatilai@redhat.com>
Subject: Re: [dpdk-dev] [PATCH] eal: add option --avail-cores to detect lcores
Date: Thu, 30 Jun 2016 15:43:48 +0200 [thread overview]
Message-ID: <1672769.UR6W46hl4M@xps13> (raw)
In-Reply-To: <0f795ccf-838f-120e-84b2-81f69b279050@intel.com>
2016-05-19 10:25, Tan, Jianfeng:
> On 5/18/2016 8:46 PM, David Marchand wrote:
> > On Wed, Mar 9, 2016 at 2:05 PM, Panu Matilainen <pmatilai@redhat.com> wrote:
> >> On 03/08/2016 07:38 PM, Tan, Jianfeng wrote:
> >>> 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.
> >>
> >> 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?
> > +1 and I don't even see why we should have an option to disable this,
> > since taskset would do the job.
> >
> > Looking at your special case, if the user did set an isolcpus option
> > for another use, with no -c/-l, I understand the dpdk application
> > won't care too much about it.
> > So, this seems like somehow rude to the rest of the system and unwanted.
>
> The case you mentioned above is not the case I mean. But you make your
> point about this one.
> The case I originally mean: user sets an isolcpus option for DPDK
> applications. Originally, DPDK apps would be started without any
> problem. But for now, fail to start them because the required cores are
> excluded before -c/-l. As per your comments following, we can add a
> warning message (or should we quit on this situation?). But it indeed
> has an effect on old users (they should changed to use "taskset
> ./dpdk_app ..."). Do you think it's a problem?
There is no activity on this patch.
Jianfeng, do not hesitate to ping if needed.
Should we class this patch as "changes requested"?
next prev parent reply other threads:[~2016-06-30 13:43 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
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 [this message]
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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