Not logged in
Log in now
Create an account
Subscribe to LWN
LWN.net Weekly Edition for December 5, 2013
Deadline scheduling: coming soon?
LWN.net Weekly Edition for November 27, 2013
ACPI for ARM?
LWN.net Weekly Edition for November 21, 2013
How did you determine that the Android guys' avoidance of user-mode daemons was strictly due to performance issues?
Posted Jan 5, 2012 22:51 UTC (Thu) by dlang (✭ supporter ✭, #313)
Posted Jan 5, 2012 23:13 UTC (Thu) by dlang (✭ supporter ✭, #313)
Posted Jan 6, 2012 16:35 UTC (Fri) by PaulMcKenney (subscriber, #9624)
One caution: It is difficult to get requirements from the Android guys. Not because they are uncooperative, but because they are only conscious of some of the requirements. The rest are so second-nature to them that they don't think of them. This means that working on a suitable replacement is an iterative process, where you learn the requirements by repeatedly implementing your best guess at each point in time.
John Stultz has gone through much of this process with his alarm-timers work, and he does appear to be getting close to a solution that is useful to both the Android guys and to non-smartphone software.
I have been on both sides of this. Back in the 1990s, those of us at Sequent habitually wrote parallel programs, but could not describe how to do it to others. We did try, but the results were not so good. Instead, we used apprenticeship-style training: We put the new guy in a cube surrounded by people who knew parallel programming, and after a few months, the new guy would have no problem writing competent parallel code.
I was on the other side while gathering wakelock requirements in 2010 and 2011. The “Avoid Thundering Herds of Timers” requirement is an example of an important requirement that was not at all obvious to me, but so obvious to the Android guys that they didn't think to state it.
Sort of like you would probably not see the need to put “the acceleration of gravity at the site is 9.8 meters per second squared” when creating specs for a builder. ;–)
Posted Jan 12, 2012 23:20 UTC (Thu) by Kluge (guest, #2881)
Does this mean that Android developers are from Mars, kernel hackers from Venus? ;-)
Mars and Venus
Posted Jan 13, 2012 0:54 UTC (Fri) by PaulMcKenney (subscriber, #9624)
Copyright © 2013, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds