[Dovecot] v2.0.alpha1 released

[Ed W]

Timo Sirainen wrote:
> On Tue, 2009-10-13 at 21:38 +0100, Ed W wrote:
>   
>> Something I had been pondering recently (I started using a cell phone 
>> with imap idle support), was a previous poster mentioning the huge 
>> increase in battery life from turning off the radio for as long as 
>> possible. It appears that just turning on the radio (wifi or 3G) 
>> consumes much more energy than the transmitting of a few bytes of data 
>> after it's on.  In particular synchronising certain types of infrequent 
>> transmissions may have a dramatic increase in battery life for mobile 
>> devices - I'm thinking mainly of the NOOPs when the connection is idling
>>
>> Is this something that could be implemented with the current 
>> architecture?  Are there other types of application where synchronising 
>> "stuff" happening to multiple connections from the same client could be 
>> helpful?
>>     
>
> No matter how many times I read the above, I've no idea what you're
> trying to ask. :) This seems like entirely a client-dependent issue and
> Dovecot can't much alter clients' behavior. Unless you're talking about
> running Dovecot on a cell phone?..
>   

Perhaps I misunderstand, but doesn't dovecot send a "keepalive" on 
connections which are idling?  It's been discussed on the list 
previously, google turns up this (not from the list, but related):
    http://doubleukay.com/node/12

I hadn't previously twigged for example that the real reason using my 
old Nokia N95 as a wifi SIP phone was caning the battery could have been 
the short re-registration interval as much as actually having the phone 
on wifi.  I now have an N97 and the buggers disabled the SIP phone bit, 
but there is some hope it will be re-enabled on the next firmware update 
- I was planning to do a bit of research on this if so.

The point being that for wireless users there is a massive "cost" to 
turn on the radio and transmit any data, the actual transmission of 
incremental data after that is cheap.  So applications and servers which 
may operate over wireless networks can massively increase battery life 
if they give some thought to significantly "batching up" network traffic

I can imagine that in the case of a typical cell phone with say 3 email 
accounts, there will be likely three idle connections (or more) to 
dovecot and each will end up sending keepalive packets at slightly 
different intervals for each connection.  By synchronising this network 
traffic you would potentially increase battery life by up to a factor of 
3 (ie turn on the radio to send the keepalive for all connections in one 
go, rather than turning the radio on three times as often)... (I think 
perhaps that's optimistic, but you can see that quite large gains might 
be possible here)

Nokia make a rather neat battery optimisation tool which allows you to 
log power consumed very precisely (and hopefully to correlate it to what 
your app is doing) - I would like to find the time to break this out to 
have a closer peak at some of this stuff, but it remains on my todo list 
right now...

Cheers

Ed W