option FIB_ALGO and dpdk_lpm4

[Marek Zarychta]

W dniu 24.02.2021 o 22:40, Alexander V. Chernikov pisze:
> 24.02.2021, 10:50, "Olivier Cochard-Labbé" <olivier at freebsd.org>:
>> On Wed, Feb 24, 2021 at 1:22 AM Marek Zarychta <
>> zarychtam at plan-b.pwste.edu.pl> wrote:
>>
>>>  >
>>>
>>>  Please let me ask only one final question. Does adding:
>>>
>>>  net.route.algo.inet.algo=dpdk_lpm4
>>>  net.route.algo.inet6.algo=dpdk_lpm6
>>>
>>>  to /etc/sysctl.conf make any sense? I see that right FIB_ALGO is
>>>  automatically picked up when the module is available.
>>
>> My understanding is the network stack will switch to the optimum algorithm
>> regarding the number of routes installed.
>> cf "Automatic algorithm selection" chapter here:
>> https://reviews.freebsd.org/D27401
>>
>> So you don't need to set this sysctl.
> To add some points to Olivier's explanation:
> indeed, algorithm selection SHOULD happen automatically.
> Some things to keep in mind: when the BGP sessions flaps kernel routes may go from the full-view to near-zero and vice versa.
> In that case, automatic selection will switch to lockless_radix for the range between 10..1000 routes (or similar). Lockless radix schedules rebuild for every change, so the speed of deleting/adding first 1k routes may be slower than expected.

Hello Olivier and Alexander,
thank you for explaining this. As far as I have tested setting this from
sysctl.conf works for current fib. So to avoid early switching of route
algorithms and speed up initial filling of route tables with 850k+ ip
routes and 100k+ ip6 routes I'll keep both those setting in
/etc/sysctl.conf.


-- 
Marek Zarychta

-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_signature
Type: application/pgp-signature
Size: 495 bytes
Desc: OpenPGP digital signature
URL: <http://lists.freebsd.org/pipermail/freebsd-net/attachments/20210225/5be7b633/attachment.sig>