[kea-dev] kea apache cassandra/datastax cassandra

Razvan Becheriu razvan.becheriu at qualitance.com
Thu May 19 14:44:40 UTC 2016


Hi,

I did the implementation directly in the KEA server. I did not use any
hooks for the cassandra backend support.
I did not perform stress tests on the cassandra implementation.

Regards,
Razvan

On Thu, May 19, 2016 at 5:21 PM, Angelo Failla <pallotron at fb.com> wrote:

> Nice!
>
>
>
> Have you stress tested your patch with perfdhcp with, say, 1500 RPS?
>
>
>
> As I wrote in a previous thread [1] KEA is a mono threaded application and
> your hook might not perform as expected if your backend is slow (e.g.
> between 20ms and 50ms).
>
> Even if your backend takes 8ms to respond you will probably still max out
> at 125 RPS (best conditions).
>
> This is because when a request is being served all the incoming udp
> packets will be buffered in kernel space, and processed sequentially… and
> if your hook is not fast enough your network recvq will max out until it
> hits the kernel buffer limits, after which you will start dropping packets.
>
>
>
> You might need to alternatives solutions to this. For example the solution
> we use in Facebook (in our hook) is to drop the first DISCOVERY/SOLICIT
> request, spawn a background fetch to our backend, which populate internal
> data structure in memory, when the client retries a second or so later the
> info will be in memory and therefore it can be served fast. We basically
> take advantage of the fact that clients usually have retry/exponential
> backoff logic.
>
>
>
> If you run into performance issues (like we did) you might find my
> proposal viable (until and if KEA people will consider redesign the core to
> be async or multithread).
>
>
>
> [1] https://lists.isc.org/pipermail/kea-dev/2016-March/000628.html
>
> --
>
> Angelo Failla
>
> Cluster Infrastructure - Dublin
>
> Pallotron at fb.com
>
>
>
> *From: *<kea-dev-bounces at lists.isc.org> on behalf of Razvan Becheriu <
> razvan.becheriu at qualitance.com>
> *Date: *Thursday, May 19, 2016 at 9:58 AM
> *To: *"kea-dev at lists.isc.org" <kea-dev at lists.isc.org>
> *Subject: *[kea-dev] kea apache cassandra/datastax cassandra
>
>
>
> Hi,
>
>
>
> My name is Razvan Becheriu.
>
>
>
> I work for Qualitance in collaboration with Deutsche Telekom.
>
> I have been working on improving the KEA server by adding support for
> apache cassandra/datastax cassandra.
>
> From my understanding, the new source files will be commited with "Apache
> License".
>
>
>
> I am ready to commit the changes to a separate branch (for code review).
> The source files have been updated to latest (main branch) version.
>
>
>
> One thing to mention is that not all unit tests have been written for the
> cassandra backend.
>
>
>
> Please let me know how to proceed.
>
>
>
> Regards,
>
> Razvan
>
>
>
>
>
>
> --
>
> *Razvan Becheriu*  |  senior software engineer  |  QUALITANCE™
> *RO:* +00 (000) 000 000  |  *office:* +40 (372) 944 741
> Opera Center bldg. 2, fl. 7-8, 2 Dr. Nicolae D. Staicovici, Bucharest
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-- 
*Razvan Becheriu*  |  senior software engineer  |  QUALITANCE™
*RO:* +00 (000) 000 000  |  *office:* +40 (372) 944 741
Opera Center bldg. 2, fl. 7-8, 2 Dr. Nicolae D. Staicovici, Bucharest 050556
<https://www.google.ro/maps/place/QUALITANCE/@44.433653,26.079464,17z/data=!4m6!1m3!3m2!1s0x40b1ff173c5bc0b9:0x7226343f810c7ede!2sQUALITANCE!3m1!1s0x40b1ff173c5bc0b9:0x7226343f810c7ede?hl=ro>
razvan.becheriu at qualitance.com  |  www.qualitance.com
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