* [dpdk-dev] Feature Discussion: CPU topology detection on FreeBSD
@ 2021-01-28 4:07 Oscar Zhao
2021-01-29 10:05 ` Bruce Richardson
0 siblings, 1 reply; 6+ messages in thread
From: Oscar Zhao @ 2021-01-28 4:07 UTC (permalink / raw)
To: dev
Hello dpdk devs,
I would like to discuss the feasibility of implementing CPU topology detection on FreeBSD. Currently both eal_cpu_core_id() and eal_cpu_socket_id() in rte_eal library always return 0 on FreeBSD, making NUMA-aware development impossible without resorting to external libraries or system APIs.
The CPU topology information is available via sysct kern.sched.topology_spec. The only issue is that the return value is an XML formatted object (see https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299/). (https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299/) I'm not sure how feasible it is to parse XML inside DPDK.
On a side note, obtaining the physical NUMA node id of a core is easy - sysctl dev.cpu.[cpu#].%domain returns the corresponding node id but I have yet found a straightforward way to detect hyperthreads besides the XML thing.
Oscar
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [dpdk-dev] Feature Discussion: CPU topology detection on FreeBSD
2021-01-28 4:07 [dpdk-dev] Feature Discussion: CPU topology detection on FreeBSD Oscar Zhao
@ 2021-01-29 10:05 ` Bruce Richardson
2021-01-29 12:52 ` Burakov, Anatoly
0 siblings, 1 reply; 6+ messages in thread
From: Bruce Richardson @ 2021-01-29 10:05 UTC (permalink / raw)
To: Oscar Zhao; +Cc: dev
On Thu, Jan 28, 2021 at 04:07:07AM +0000, Oscar Zhao wrote:
> Hello dpdk devs,
>
> I would like to discuss the feasibility of implementing CPU topology detection on FreeBSD. Currently both eal_cpu_core_id() and eal_cpu_socket_id() in rte_eal library always return 0 on FreeBSD, making NUMA-aware development impossible without resorting to external libraries or system APIs.
>
> The CPU topology information is available via sysct kern.sched.topology_spec. The only issue is that the return value is an XML formatted object (see https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299/). (https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299/) I'm not sure how feasible it is to parse XML inside DPDK.
>
> On a side note, obtaining the physical NUMA node id of a core is easy - sysctl dev.cpu.[cpu#].%domain returns the corresponding node id but I have yet found a straightforward way to detect hyperthreads besides the XML thing.
>
> Oscar
Even adding in the numa node information would be a welcome start.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [dpdk-dev] Feature Discussion: CPU topology detection on FreeBSD
2021-01-29 10:05 ` Bruce Richardson
@ 2021-01-29 12:52 ` Burakov, Anatoly
2021-01-29 13:45 ` Bruce Richardson
2021-01-29 22:24 ` Oscar Zhao
0 siblings, 2 replies; 6+ messages in thread
From: Burakov, Anatoly @ 2021-01-29 12:52 UTC (permalink / raw)
To: Bruce Richardson, Oscar Zhao; +Cc: dev
On 29-Jan-21 10:05 AM, Bruce Richardson wrote:
> On Thu, Jan 28, 2021 at 04:07:07AM +0000, Oscar Zhao wrote:
>> Hello dpdk devs,
>>
>> I would like to discuss the feasibility of implementing CPU topology detection on FreeBSD. Currently both eal_cpu_core_id() and eal_cpu_socket_id() in rte_eal library always return 0 on FreeBSD, making NUMA-aware development impossible without resorting to external libraries or system APIs.
>>
>> The CPU topology information is available via sysct kern.sched.topology_spec. The only issue is that the return value is an XML formatted object (see https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299/). (https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299/) I'm not sure how feasible it is to parse XML inside DPDK.
>>
>> On a side note, obtaining the physical NUMA node id of a core is easy - sysctl dev.cpu.[cpu#].%domain returns the corresponding node id but I have yet found a straightforward way to detect hyperthreads besides the XML thing.
>>
>> Oscar
>
> Even adding in the numa node information would be a welcome start.
>
There's little value in it though, because as far as i'm aware we can't
allocate memory on specific NUMA nodes in FreeBSD.
--
Thanks,
Anatoly
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [dpdk-dev] Feature Discussion: CPU topology detection on FreeBSD
2021-01-29 12:52 ` Burakov, Anatoly
@ 2021-01-29 13:45 ` Bruce Richardson
2021-02-10 16:01 ` Burakov, Anatoly
2021-01-29 22:24 ` Oscar Zhao
1 sibling, 1 reply; 6+ messages in thread
From: Bruce Richardson @ 2021-01-29 13:45 UTC (permalink / raw)
To: Burakov, Anatoly; +Cc: Oscar Zhao, dev
On Fri, Jan 29, 2021 at 12:52:50PM +0000, Burakov, Anatoly wrote:
> On 29-Jan-21 10:05 AM, Bruce Richardson wrote:
> > On Thu, Jan 28, 2021 at 04:07:07AM +0000, Oscar Zhao wrote:
> > > Hello dpdk devs,
> > >
> > > I would like to discuss the feasibility of implementing CPU topology detection on FreeBSD. Currently both eal_cpu_core_id() and eal_cpu_socket_id() in rte_eal library always return 0 on FreeBSD, making NUMA-aware development impossible without resorting to external libraries or system APIs.
> > >
> > > The CPU topology information is available via sysct kern.sched.topology_spec. The only issue is that the return value is an XML formatted object (see https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299/). (https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299/) I'm not sure how feasible it is to parse XML inside DPDK.
> > >
> > > On a side note, obtaining the physical NUMA node id of a core is easy - sysctl dev.cpu.[cpu#].%domain returns the corresponding node id but I have yet found a straightforward way to detect hyperthreads besides the XML thing.
> > >
> > > Oscar
> >
> > Even adding in the numa node information would be a welcome start.
> >
>
> There's little value in it though, because as far as i'm aware we can't
> allocate memory on specific NUMA nodes in FreeBSD.
>
That is because the NUMA support in FreeBSD was not in place when we first
did the DPDK port. However, I still see no reason not to start adding it
now, even if it is only for information purposes at this point.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [dpdk-dev] Feature Discussion: CPU topology detection on FreeBSD
2021-01-29 12:52 ` Burakov, Anatoly
2021-01-29 13:45 ` Bruce Richardson
@ 2021-01-29 22:24 ` Oscar Zhao
1 sibling, 0 replies; 6+ messages in thread
From: Oscar Zhao @ 2021-01-29 22:24 UTC (permalink / raw)
To: Bruce Richardson, Burakov, Anatoly; +Cc: dev
FreeBSD rolled their own NUMA memory APIs on 12.0 (see https://www.freebsd.org/cgi/man.cgi?query=cpuset_getdomain&sektion=2&apropos=0&manpath=FreeBSD+12.2-RELEASE+and+Ports). These syscalls allow binding of a process/thread/jail memory allocation to a specific NUMA domain.
I think the first step is to support correct NUMA detection. The "de facto" way of doing that is parsing the XML output from the cpu topology sysctl. I'm not sure how viable it is in DPDK without introducing external dependencies. I've also been playing with the hwloc library which supposedly offers portable topology detection.
If both options are not feasible maybe something can be done on the FreeBSD side first.
January 29, 2021 8:45 AM, "Bruce Richardson" <bruce.richardson@intel.com> wrote:
> On Fri, Jan 29, 2021 at 12:52:50PM +0000, Burakov, Anatoly wrote:
>
>> On 29-Jan-21 10:05 AM, Bruce Richardson wrote:
>> On Thu, Jan 28, 2021 at 04:07:07AM +0000, Oscar Zhao wrote:
>>> Hello dpdk devs,
>>>
>>> I would like to discuss the feasibility of implementing CPU topology detection on FreeBSD.
>> Currently both eal_cpu_core_id() and eal_cpu_socket_id() in rte_eal library always return 0 on
>> FreeBSD, making NUMA-aware development impossible without resorting to external libraries or system
>> APIs.
>>>
>>> The CPU topology information is available via sysct kern.sched.topology_spec. The only issue is
>> that the return value is an XML formatted object (see
>> https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299).
>> (https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299) I'm not sure how feasible it is
>> to parse XML inside DPDK.
>>>
>>> On a side note, obtaining the physical NUMA node id of a core is easy - sysctl
>> dev.cpu.[cpu#].%domain returns the corresponding node id but I have yet found a straightforward way
>> to detect hyperthreads besides the XML thing.
>>>
>>> Oscar
>>
>> Even adding in the numa node information would be a welcome start.
>>
>> There's little value in it though, because as far as i'm aware we can't
>> allocate memory on specific NUMA nodes in FreeBSD.
>
> That is because the NUMA support in FreeBSD was not in place when we first
> did the DPDK port. However, I still see no reason not to start adding it
> now, even if it is only for information purposes at this point.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [dpdk-dev] Feature Discussion: CPU topology detection on FreeBSD
2021-01-29 13:45 ` Bruce Richardson
@ 2021-02-10 16:01 ` Burakov, Anatoly
0 siblings, 0 replies; 6+ messages in thread
From: Burakov, Anatoly @ 2021-02-10 16:01 UTC (permalink / raw)
To: Bruce Richardson; +Cc: Oscar Zhao, dev
On 29-Jan-21 1:45 PM, Bruce Richardson wrote:
> On Fri, Jan 29, 2021 at 12:52:50PM +0000, Burakov, Anatoly wrote:
>> On 29-Jan-21 10:05 AM, Bruce Richardson wrote:
>>> On Thu, Jan 28, 2021 at 04:07:07AM +0000, Oscar Zhao wrote:
>>>> Hello dpdk devs,
>>>>
>>>> I would like to discuss the feasibility of implementing CPU topology detection on FreeBSD. Currently both eal_cpu_core_id() and eal_cpu_socket_id() in rte_eal library always return 0 on FreeBSD, making NUMA-aware development impossible without resorting to external libraries or system APIs.
>>>>
>>>> The CPU topology information is available via sysct kern.sched.topology_spec. The only issue is that the return value is an XML formatted object (see https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299/). (https://forums.freebsd.org/threads/number-of-cpus-and-cores.41299/) I'm not sure how feasible it is to parse XML inside DPDK.
>>>>
>>>> On a side note, obtaining the physical NUMA node id of a core is easy - sysctl dev.cpu.[cpu#].%domain returns the corresponding node id but I have yet found a straightforward way to detect hyperthreads besides the XML thing.
>>>>
>>>> Oscar
>>>
>>> Even adding in the numa node information would be a welcome start.
>>>
>>
>> There's little value in it though, because as far as i'm aware we can't
>> allocate memory on specific NUMA nodes in FreeBSD.
>>
>
> That is because the NUMA support in FreeBSD was not in place when we first
> did the DPDK port. However, I still see no reason not to start adding it
> now, even if it is only for information purposes at this point.
>
A lot of DPDK apps will fail to work in this case, because most of them
will allocate with an explicit NUMA node. So, if you have a NUMA node
assigned to an lcore but can only allocate from NUMA node 0, any
allocation explicitly targeting NUMA node 1 will not succeed.
--
Thanks,
Anatoly
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-02-10 16:02 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2021-01-28 4:07 [dpdk-dev] Feature Discussion: CPU topology detection on FreeBSD Oscar Zhao
2021-01-29 10:05 ` Bruce Richardson
2021-01-29 12:52 ` Burakov, Anatoly
2021-01-29 13:45 ` Bruce Richardson
2021-02-10 16:01 ` Burakov, Anatoly
2021-01-29 22:24 ` Oscar Zhao
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