Re: rgw multisite: revisiting the design of 'async notifications'

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



It seems like some of the confusion arises from the fact that the
consumers aren't actually programmed to back off/quiesce as the
polling-avoidance strategy expects.

Matt

On Wed, Mar 23, 2022 at 9:46 AM Yehuda Sadeh-Weinraub <yehuda@xxxxxxxxxx> wrote:
>
> On Tue, Mar 22, 2022 at 2:14 PM Adam C. Emerson <aemerson@xxxxxxxxxx> wrote:
> >
> > On 22/03/2022, Matt Benjamin wrote:
> > > Just to be clear, why do we think it doesn't serve as an optimization?
> >
> > My thought being, if we're already saturated with syncing stuff,
> > adding more work on top of it won't help anything.
>
> And what if we're not saturated? You're optimizing the high traffic
> case by killing the low traffic case. If there are specific
> implementation issues then address them, but I think this is very
> valuable to some use cases.
>
> Yehuda
>
> >
> > > OTOH, as Yehuda points out, the intended purpose of the async
> > > notifies was to implement polling avoidance--to provide wake-ups to
> > > sync endpoints that might otherwise sleep/idle as replication events
> > > accumulate.  This is a well established design pattern, and if we
> > > remember that the async notifies are duplicating hints, it seems to
> > > make sense.
> >
> > Measuring to see how consequential this is would be legitimate.
> >
> > I can imagine a world where if the primary has an idea what the
> > secondary's polling period is, and there hasn't been much sync
> > activity and the primary knows the secondary won't poll for a while,
> > it might be worthwhile to send a single wakeup event when there's new
> > data available telling it that there's new stuff in the data log.
> >
> > Whether this is worthwhile would depend heavily on how frequently the
> > secondary polls the data log in the first place.
> >
> > _______________________________________________
> > Dev mailing list -- dev@xxxxxxx
> > To unsubscribe send an email to dev-leave@xxxxxxx
> >
>
> _______________________________________________
> Dev mailing list -- dev@xxxxxxx
> To unsubscribe send an email to dev-leave@xxxxxxx
>


-- 

Matt Benjamin
Red Hat, Inc.
315 West Huron Street, Suite 140A
Ann Arbor, Michigan 48103

http://www.redhat.com/en/technologies/storage

tel.  734-821-5101
fax.  734-769-8938
cel.  734-216-5309

_______________________________________________
Dev mailing list -- dev@xxxxxxx
To unsubscribe send an email to dev-leave@xxxxxxx



[Index of Archives]     [CEPH Users]     [Ceph Devel]     [Ceph Large]     [Information on CEPH]     [Linux BTRFS]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux