Mavericks Preview: Timer Coalescing boosts Mac laptop battery life

Timer Coalescing

A lot of the time your CPU isn't doing anything, and we're not just talking about when you're away from your keyboard - even when you're working, the CPU could be powered down but isn't. OS X Mavericks will use a technique called Timer Coalescing to make the most of this downtime, and that means battery life will last much longer.

Of the many advanced technologies being introduced in OS X Mavericks, one of the most useful for Mac laptop users is Timer Coalescing. It's an energy-saving technique that promises to extend battery life on your Mac laptop by forcing the laptop's CPU into a low-power mode whenever it's available.

Here's what Apple says about Timer Coalescing:

In OS X Mavericks, Timer Coalescing groups low-level operations together, creating tiny periods of idle time that allow your CPU to enter a low-power state more often.

Managing CPU traffic

In the space of a few seconds, your CPU will spike in activity many times. This is not only because of the applications you're running, but also because of all the other housekeeping tasks needed to keep OS X up and running. In between those moments, your Mac's CPU enters an idle state, where it's not doing much of anything.

To wake from that idle state requires power, and using power means the battery of your MacBook Air or MacBook Pro won't last as long. And right now, in Mountain Lion and earlier revisions of OS X, your Mac isn't doing it as efficiently as it could be.

That means power is getting wasted, and your Mac laptop is draining its battery faster than it has to be. That's because many of those low-level operations are spread apart, over milliseconds, but it adds up pretty quickly.

Mavericks Preview: Timer Coalescing idle

Timer Coalescing changes that by grouping together those operations, so instead of constantly flickering between an idle state and operation, the CPU stays idle longer. It may only stay idle for a fraction of a second, compared to a few milliseconds, but over minutes and hours, that idle state adds up. The net result is that your Mac's CPU uses less power. A lot less power.

In its tests, Apple compared Mountain Lion and a development build of Mavericks running on a production MacBook Air. They discovered that Timer Coalescing can reduce CPU activity by 72 percent.

Mavericks Preview: CPU usage

The way Timer Coalescing works, you won't notice any difference in performance. The operating system is just grouping together the tasks that need to happen to make it run more efficiently. And there's nothing you need to do to get it working - it's built right in to Mavericks.

Apple has a nifty interactive graphic on its web site that will show you how Timer Coalescing works.

I don't know a single Mac laptop user who doesn't wish their device didn't last longer on a single charge. And in fairness to Apple, nothing they can do will make the battery last long enough for everyone. But Timer Coalescing goes a long way to improving battery life without negatively impacting system performance - I think we can all agree that it's a huge step forward.

Is Timer Coalescing an important feature for you? Have you used other operating systems (like Windows 7) that support Timer Coalescing? Let us know what you think in the comments, and click these links for more Mavericks info!

Have something to say about this story? Share your comments below! Need help with something else? Submit your question!

Peter Cohen

Managing Editor of iMore, Mac and gaming specialist and all-around technologist. Follow him on Twitter @flargh

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Reader comments

Mavericks Preview: Timer Coalescing boosts Mac laptop battery life

5 Comments

@Peter As a iMore fan who just converted to a Macbook Pro about 3 weeks ago I truly appreciate all the write ups you have been doing lately. Though I don't have Mavericks loaded yet (I'm not a developer) I value the information you provide on the new OSX as well as all other things Mac related. It has definitely made my transition a pleasant one to say the least. :)

Thank you so much, Daytona! If you have any questions, feel free to ask (or hit the forums for more help). And welcome to the Mac fold!

Wow, didn't know Windows 7 had this... only seemed to be slightly better than XP on the same/similar hardware. Hopefully it makes more of a difference in Mavericks

If I'm running Mavericks on my iMac/Mac Mini, can I expect it to use less energy and run cooler than it does currently for the same reasons?

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