From: "Oscar Zhao" <oz@quacker.org>
To: "Bruce Richardson" <bruce.richardson@intel.com>,
"Burakov, Anatoly" <anatoly.burakov@intel.com>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] Feature Discussion: CPU topology detection on FreeBSD
Date: Fri, 29 Jan 2021 22:24:48 +0000 [thread overview]
Message-ID: <cd79629ba7fa436a0216b3930cb30539@quacker.org> (raw)
In-Reply-To: <20210129134511.GF929@bricha3-MOBL.ger.corp.intel.com>
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.
prev parent reply other threads:[~2021-01-29 23:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-28 4:07 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 [this message]
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