Suggestion: Use delta-RPM (presto) for bandwidth efficient updates

asked 2013-12-25 16:27:12 +0300

MartinK
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updated 2013-12-27 19:57:05 +0300

eric

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https://twitter.com/erkki...

As Jolla is a mobile device, available Internet bandwidth might be sometimes severely limited (2G, data cap reached, etc.), preventing the download of bigger updates.

What is delta-RPM/presto ?

In short, it makes it possible to download only the the diff from the last package version and creating the updated package on-device by applying the diff on the old package.

Advantages

should save a lot of bandwidth
makes updates over mobile data connection more feasible

Potential disadvantages

packages will need to be stored, so that the diff can be applied to them
some processing needs to be done to apply the diff

Is this already used elsewhere?

The Fedora Linux distribution has been using delta-RPM/Presto by default since version 11, so for about 4-5 years already.

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answered 2013-12-25 17:37:09 +0300

wstephenson
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/etc/zypp/zypp.conf leaves the default setting of

download.use_deltarpm = true

so it's just a matter of the repos providing deltarpms.

It would be interesting to see which option sucks most battery.

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answered 2013-12-25 17:26:08 +0300

pcfe

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http://www.pcfe.net/

updated 2014-04-27 15:35:52 +0300

UI elements to add: have a toggle (I, personally, would expect to find this under Preferences / System Settings / About product in the pulley menu) for the user to choose between saving bandwidth and saving CPU cycles (ideally after testing to see just how much assembling the 10 largest packages would cost)

Clarification: When roaming I would set it to save bandwidth, when on a WLAN or with enough mobile data left for the month I would opt for speed over bandwidth. Hence the request for a toggle.

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answered 2014-02-28 18:44:22 +0300

Xeno_PL
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Actually I think it can be quite counterproductive. Even on my i7 equipped lappy, downloading full packages faster than download delta and rebuild RPM. The only good reason would be saving costs when updates have to be downloaded over mobile data.

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Comments

It’s probably less I/O load for the servers, once the deltas are computed. That would be another reason.

sami.boukortt ( 2014-03-01 00:23:17 +0300 )edit

@sami.boukortt but not less io for the jolla device.. the update process would actually take much longer with delta rpm'es.

tigeli ( 2014-04-28 10:59:26 +0300 )edit

Another possibility would be to use OSTree - it works with versioned filesystem trees and supports differential tree updates, atomic tree switching and rollback. The project is a bit new, but pretty active.

MartinK ( 2014-04-28 20:49:51 +0300 )edit

Suggestion: Use delta-RPM (presto) for bandwidth efficient updates

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