Re: Persistent Bucket Notification performance

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Hi,

Thanks for the quick response, I have the notifications going to a http
endpoint running on one of the RGW's machines so the latency is as low as I
can make it for both methods. If the limiting factor is at the rados layer
my only tuning options are to put the rgw log pool on the fastest media i
have available ?



On Thu, 24 Nov 2022 at 13:37, Yuval Lifshitz <ylifshit@xxxxxxxxxx> wrote:

> Hi Steven,
> When using synchronous (=non-persistent) notifications, the overall rate
> is dependent on the latency between the RGW and the endpoint to which you
> are sending the notifications. The protocols for sending the
> notifications (kafka/amqp) are using batches and are usually very
> efficient. However, if there is latency, this would slow down the RGW.
>
> When using asynchronous (=persistent) notifications, they are written to a
> RADOS-backed queue by the RGW that received the request, and then pulled
> from that queue by some other (or sometimes the same) RGW that sends the
> notifications to the endpoint.
> Pulling from the queue, and sending the notifications is usually very
> fast, however, writing to the notification queue is a RADOS operation. The
> amount of information written to the queue is usually small but still has
> the RADOS overhead, as the notifications are written one-by-one. So, in
> this case, the limiting factor would be the RADOS IOpS.
>
> Please let me know if this clarifies the behavior you observe?
>
> Yuval
>
> On Thu, Nov 24, 2022 at 1:27 PM Steven Goodliff <sgoodliff@xxxxxxxxx>
> wrote:
>
>> Hi,
>>
>> I'm really struggling with persistent bucket notifications running 17.2.3.
>> I can't get much more than 600 notifications a second but when changing to
>> async then i see higher rates using the following metric
>>
>> sum(rate(ceph_rgw_pubsub_push_ok[$__rate_interval]))
>>
>> I believe this is mainly down to being throttled by using 1 rgw rather
>> than
>> all the rgw's the async method allows.
>>
>> We would prefer to use persistent but can't get the throughput we need,
>> any
>> suggestions would be much appreciated.
>>
>> Thanks
>>
>> Steven
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