Hi,
We don't have any developer guide. In general, every network card has different
characteristic and features, so it's almost impossible to provide a
comprehensive
manual for that.
Daniel
On 4/3/19 11:53 AM, Sergey Petrov wrote:
> On Wed, 2019-04-03 at 10:52 +0200, Petr Špaček wrote:
>> On 03. 04. 19 10:45, Sergey Petrov wrote:
>>> I perfoms benchmarks with knot-dns as a authoritative server and dnsperf
>>> as a workload client. Knot server has 32 cores. Interrupts from 10Gb
>>> network card are spreaded across all 32 cores. Knot configured with
>>> 64 udp-workers. Each knot thread assigned to one core. So there are at
>>> least two knot threads assigned to one core. Then i start dnsperf with
>>> command
>>>
>>> ./dnsperf -s 10.0.0.4 -d out -n 20 -c 103 -T 64 -t 500 -S 1 -q 1000 -D
>>>
>>> htop on knot server shows 3-4 cores completly unused. Then i restart
>>> dnsperf unused cores are changes.
>>>
>>> That is the reason for unused core?
>>
>> Well, sometimes dnsperf is too slow :-)
>>
>> I recommend to check this:
>> - Make sure dnsperf ("source machine") is not 100 % utilized.
>> - Try to increase number of sockets used by dnsperf, i.e. -c parameter.
>> I would try also values like 500 and 1000 to see if it makes any
>> difference. It might change results significantly because Linux kernel
>> is using hashes over some packet fields and low number of sockets might
>> result in uneven query distribution.
>>
>> Please let us know what are your new results.
>>
>
> The source machne is about 15% utilized.
>
> ./dnsperf -s 10.0.0.4 -d out -n 20 -c 512 -T 512 -t 500 -S 1 -q 1000 -D
>
> get us some performance penalty (260000 rps VS 310000 rps) and more even
> distribution across all cores with 100% usages of all eight cores on
> last CPU socket. While other CPU socket cores are aproximately 60%
> loaded.
>
> Using "-c 1000 -T 1000" parameters of dnsperf i see practicaly the same
> core load distribution and even more performance penalty.
>
> Using "-c 16 -T 16" parameters i see 14 0% utilized cores, 16 100%
> utilized cores and 2 50% utilized cores with about 300000 rps
>
> The question is that prevents knot thread on 0% used core to serve a
> packet arrived with IRQ bounded to another core? May be you have some
> developer guide can answer this question?
>
>
>
>
>
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