What is CPU frequency scaling?
One of the most important (and obvious) characteristics of mobile computing is that mobile devices use batteries rather than being plugged into the mains power. This means that every part of a mobile system needs to be tuned to save as much power as possible yet while offering the best performance available. Normally these two demands (efficiency and performance) are at odds with each other. The higher the performance, the higher the power consumption and heat generated. On the desktop this isn’t so much of a problem as PCs are connected to the mains and have massive cooling fans. However that isn’t the case on mobile.
There is a direct relationship between the amount of power used by a processor and its clock frequency. In a nutshell the quicker all the transistors (gates) are switched in the chip the more power is used. How often the gates are switched is controlled by the clock frequency. You can maybe think of it as akin to the engine revs in a car, the higher the revs the more fuel consumed.
What this means is that by lowering the clock frequency the power consumption is also lowered, and that is vital for mobile computing and especially for smartphones. There is a feature in Android (via the Linux kernel) which allows the clock frequency of the processor to be varied, scaled down when the phone is not being used much and ramped up when needed.
It turns out that when the clock frequency is lower then the chip doesn’t need as many volts to run. So there is a correlation between the clock frequency and the volts needed. Therefore these two can be adjusted in tandem. Whenever the clock frequency is changed then the voltage can be changed as well. Altering them together is known as Dynamic Voltage and Frequency Scaling or DVFS for short.
What does it mean for users?
The biggest benefit for smartphone users is battery life. Since the CPU isn’t running at full power all of the time it means that while you are reading a web page or pondering your next move in a game then the CPU frequency can be scaled down to save power. Once the app needs more performance then the CPU frequency (along with the voltage) will be increased to handle the new demands. However this does show one weakness of DVFS, it is reactive. The frequency is increased as a reaction to the demand for more performance. This means that there is always a slight delay from when the extra performance is needed to when it is delivered. Thankfully that delay is almost imperceptible, however developers using profiling tools might see it, but more about that in the section below. To get around this lag, Android has one little trick, whenever the screen is touched the CPU frequency of one or more cores is boosted in anticipation of some user interface activity.
If you want to see DVFS in action then you can download an app like CPU Z. On the SoC tab you can see lots of information about your device’s processor including the make, model and number of cores. Also listed is some clock speed data. Each core is listed besides its current frequency. If you watch closely then you will see that each core has a changing clock speed. If some of the cores are stopped and the others are running at a low speed (like 300MHz or similar) then touch the screen to see how the cores react.
There is one more thing worth mentioning, the scaling governor. There is component of the Linux kernel which controls the DVFS scaling. It is called the scaling governor. The default governor is called “interactive.” It is in fact the interactive governor which ramps up the CPU frequency when the screen is touched. If you have rooted your phone it is possible to change the governor using programs like Kernel Adiutor (ROOT) or Root Booster.
There is lots of information (and sometimes, misinformation) about changing the governor to get significantly different performance/battery results from your device. If this kind of thing interests you then you could have some fun playing with the governor settings, however you can only change the governor if you have root access. It is also worth remembering that smartphone OEMs spend a lot of time and money building phones with the highest possible performance levels while maintaining a reasonable battery life. If tweaking the governor actually produced better results then you can be sure that the OEMs would do that.
What does it mean for developers?
I mentioned that the CPU scaling is reactive and not proactive. This means that there can be a lag when exiting a low frequency state of around 20 ms. If you use Android System Trace (Systrace) for profiling your apps then you can sometimes see that the first frame may not render in the 16ms time frame needed for 60 frames per second. There isn’t much that you can do about this as a developer, however knowing that this is the expected behavior will stop you chasing your tail if you see a dropped frame when coming out of a low CPU frequency.
Colt McAnlis has a brief video about “CPU Frequency Scaling” on Android. In the video he discusses how DVFS is one of those harsh realities of mobile development that you can’t control, but can have an impact on your app.
There is more…
In the last few years there have also been a number of other advances to help improve battery efficiency while boosting performance. The most important of which is probably Heterogeneous Multi-Processing (HMP) as used in ARM’s big.LITTLE system. In a HMP processor not all the cores are equal (hence Heterogeneous). In a modern 64-bit processor this would mean that a cluster of Cortex-A57 or Cortex-A72 cores would be used in conjunction with a cluster of Cortex-A53 cores. The A72 is a high performance core, while the A53 has greater energy efficiency.
What this means is that when the workload becomes two much for the LITTLE cores (Cortex-A53 in this example) then the big cores (Cortex-A72) take over. If DVFS is akin to the revs of a car engine, the big.LITTLE is like changing gears.
I have written about and benchmarked big.LITTLE processors quite extensively, if you want to know more about HMP then I can suggest the following articles: Fact or Fiction: Android apps only use one CPU core, Up close and personal: how the Samsung Galaxy S6 uses its octa-core processor, and Exynos 7420: Multitasking, multi-core and multiprocessing.
The initial implementations of the software part for big.LITTLE used the DVFS system to trigger a switch from the LITTLE cores to the big cores. Since then things have become more complex and ARM is currently working on an energy-aware scheduler for Android which will allow the Linux kernel to pick which cores run which tasks based not only on the feedback from the DVFS system but also from the Intelligent Power Allocation (IPA) algorithms and from CPU idle. There are more details in my article Energy-Aware Scheduling for Android.
So bottom line, CPU frequency scaling is good, it saves battery. When coupled with big.LITTLE, IPA and energy-aware scheduling then the battery savings are even greater.
The 2016 presidential race according to Facebook ‘likes’
The data-minded folks over at FiveThirtyEight have teamed up with Facebook to find out what parts of the country support which candidate via an interactive map. While FiveThirtyEight stresses that this is in no way a representative sample (Facebook users skew heavily younger, low-income and female, for instance), it’s still interesting to see where candidates stack up in terms of page likes.
My backyard of Kent County in Michigan has Republican neurosurgeon Ben Carson leading the way with 30 percent of likes, Vermont Democrat Bernie Sanders with 29 percent and priapic real estate mogul Donald Trump trailing at 17 percent. But judging by the rest of the map up above, that order isn’t far off from how the rest of the country is leaning.
But if likes translated directly to votes, Sanders would likely beat former Secretary of State Hillary Clinton nationwide by a 3:1 ratio, with Trump picking up more votes than Senators Ted Cruz and Marco Rubio combined.
You can even further drill down and compare candidates on a same-party, state-by-state basis as well, should you so desire. Again, it’s important to note that this isn’t anywhere close to being a scientific prediction of who will win the race for our country’s top office.
FiveThirtyEight says that another factor playing into these numbers is that “only some people on Facebook have liked a presidential candidate’s page.” Meaning, just because you support a candidate, it doesn’t mean you’ve clicked the thumbs up.
Want to do some research before you like or vote? Then give our guide to the candidates a gander.
Source: FiveThirtyEight
Runkeeper is the latest app to be bought by a shoe company
If you’re a sportswear company, then you need your own app-cum-social network to maintain relevant in this modern age. That’s why Asics has just picked up Runkeeper in a deal that’s been announced by the latter firm’s CEO, Jason Jacobs. In a post over on Medium, Jones reveals that the pair have entered into a “definitive agreement” to be bought, although he’s not revealing how much the company will cost. What is interesting, however, is that it made plenty of sense for Asics to buy the company, since Runkeeper’s data said that most of its Shoe Tracker users run with that very same brand of shoe.
Asics was one of the few big names out there that didn’t currently have a digital footprint, a worry when so many of its rivals are tooling up. For instance, Nike has been far ahead of the field with its Nike+ social network and various apps to help running and sneaker buying. Runtastic, meanwhile, was snapped up by Adidas last summer. In addition, Under Armor picked up Endomondo and MyFitnessPal for half a billion dollars combined and is working with HTC on a range of devices. It also raises questions for the last few really well-known fitness apps that are yet to be picked up — making us all wonder what Strava’s gotta do to get some love.
Via: The Next Web
Twitter’s out-of-order timeline prompts TfL to narrow travel updates
Transport for London (TfL) runs a whole host of Twitter accounts designed to keep commuters up to date with travel disruptions. The organisation is now changing its approach, however, and reducing its overall tweet output for minor delays and incidents. Why? Well, because of “various changes” that Twitter has made to users’ timelines. The organisation doesn’t blame any specific features, mentioning instead how “selected content on Twitter is (now) shown out of sequence.” In response, certain accounts will soon be tweaked. The handles for the Underground lines, for instance (@bakerlooline, @circleline, etc.) will switch from real-time service updates to focused news and alerts for major disruptions.
In a blog post, TfL has documented some of Twitter’s major experiments and feature additions since 2009. These include the now abandoned Discover tab, the While You Were Away catchup service and Moments. Notably, the list ends with a line on the company’s new timeline option, introduced earlier this week, that promises to show a selection of highly ranked tweets at the top of your feed. The service is opt-in, but with its current approach TfL says it’s still worried only “high impact and important updates would be likely to reach customers.”
It’s true that Twitter has been experimenting with features that weigh heavily on curation and algorithms. These, it hopes, will surface the best of the social network for users that don’t want to be constantly refreshing their feed. The core Twitter experience remains the same though — it’s a list of tweets in chronological order that show you conversations and moments happening right now. As a result, TfL’s minute-to-minute travel updates should still be effective. If, however, it sees Twitter’s new timeline option as a problem (regardless of whether it poses one or not) that could indicate a larger perception problem for Jack Dorsey’s company.
Source: TfL Digital Blog
Immersion sues Apple for infringing on haptic feedback patents
Apple’s the star in the latest chapter of Immersion’s court drama. The California haptic feedback developer known for going to court to guard its technologies has filed a lawsuit against Apple and AT&T. It says the haptic feedback systems of the Apple iPhone 6/6Plus, iPhone 6/6s Plus and Watch/Watch Sport/Watch Edition infringe upon two of its patents. Those are no. 8,619,051, which is named “Haptic Feedback System with Stored Effects,” and “Method and Apparatus for Providing Tactile Sensations” that’s filed under no. 8,773,356. The iPhone 6s and 6s Plus allegedly infringe upon a third patent, as well: no. 8,659,571 named “Interactivity Model for Shared Feedback on Mobile Devices.”
As Apple Insider notes, Apple’s devices have always had haptic feedback systems. However, it upgraded its newer devices’, introduced the “Taptic Engine” to its smartwatches and latest iPhones and gave them their 3D Touch/Force Touch features.
Immersion’s CEO Victor Viegas says:
While we are pleased to see others in the industry recognize the value of haptics and adopt it in their products, it is important for us to protect our business against infringement of our intellectual property in order to preserve the ecosystem we have built and the investments that we have made in continuing to advance haptic experiences. We will vigorously defend the intellectual property we have developed when it is infringed.
Besides the lawsuit in which it’s seeking damages, Immersion has also filed a complaint with the ITC “seeking an exclusion order preventing the importation, sale for importation, and sale after importation of infringing Apple devices into the United States by the defendants…” In other words, it’s requesting a sales injunction.
Back in 2008, Immersion had a better relationship with Cupertino, and it was even rumored that it would provide haptic tech for the iPhone. Apple isn’t the only tech giant that had been sued by Immersion — it also fought court battles against Microsoft in 2007 and against Motorola/Google in 2012.
[Image credit: Will Lipman]
Via: Apple Insider
Source: Immersion
UCLA open sources image detector that can see what we can’t
UCLA has released the source code to powerful image detection software that can see an object’s every detail at high speed — key for applications like fingerprint and iris scanning, or self-driving cars. It starts by identifying an object’s edges and then looking for and extracting its other, fainter features. For instance, if there are items with textured surfaces in the image, the algorithm can recognize and enhance them, as you can see in the example below the fold. It can even see through bright lights to detect their sources’ structures, such as lamps, LED lights and even the moon.
The Phase Stretch Transform algorithm was developed by UCLA professor Bahram Jalali, senior researcher Mohammad Asghari and their team. Their project is a spin-off of the university’s research on photonic time stretch that can be used to detect cancer cells. It’s also the secret behind what UCLA once called the “world’s fastest camera” that can capture events that happen very, very fast. The algorithm is now up and available to the public on GitHub and Matlab Central.
Source: UCLA
Samsung will reportedly include a Gear VR with your Galaxy S7 or Galaxy S7 Edge
Leaks are coming fast and furious about the Samsung Galaxy S7 and S7 Edge. Today we have a couple of tidbits of information to pass along that you may find interesting. First and foremost, we might be getting a hint into a major selling point for the new flagships from Korea’s largest business.
AndroidWorld.nl, a Dutch Android site, is reporting that when you purchase a Samsung Galaxy S7 or Samsung Galaxy S7 Edge, you’ll also receive a free Samsung Gear VR. This offer will apply to those who pre-order the phone between February 21 and March 10. You will then have to register your purchase on Samsung’s website.
This wouldn’t be the first time we’ve seen Samsung throw out some pretty crazy incentives to get people into their ecosystem. They were very generous in their gifts to those who signed up with Samsung Pay. Packages ranged from a fast wireless charger valued at $50 to a $200 e-coupon you could use on Samsung’s website to purchase accessories.
The Gear VR currently retails for $99.99.
The other bit of information stated in the AndroidWorld article would seem to confirm the pre-order date of the S7 and S7 Edge. In our What We Know post about the Galaxy S7, we’ve written that the phones would be announced on February 21, 2016. This date is one day before Mobile World Congress starts in Barcelona. Samsung will reportedly then hold several events around the world on February 22 to show off the new devices, including one in New York City.
Be sure to keep your eyes glued to AndroidGuys.com to stay up to date on all the leaks of the early year flagships coming out. We have posts up about the Samsung Galaxy S7 and the LG G5, which we are constantly updating.
Source: AndroidWorld via SamMobile
The post Samsung will reportedly include a Gear VR with your Galaxy S7 or Galaxy S7 Edge appeared first on AndroidGuys.
Standalone Google VR headset is also being worked on behind the scenes
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There have been quite a few rumours floating around the past few weeks that relate to Google working on a VR headset that would rival the Samsung Gear VR in the marketplace. While that VR headset would require a surrogate smartphone to work, a new report has suggested that a standalone Google VR headset is also being worked on within the walls at Google’s HQ.
While this means that Google is working on two separate VR headsets at the same time, the two couldn’t be on more different timelines. While the headset that uses smartphones is said to be releasing in 2016, with a possible cameo at Google I/O possible, the standalone headset has a less defined timeline, with some sources saying 2016 is a possibility, with another saying that the standalone project is still very much in its early development days.
If true, that is pretty big news for the virtual reality industry as Google’s significant global presence could really push VR into the mainstream, particularly if its VR headsets are built with the Nexus device mentality. Still, it sounds like we’ll have to wait until Google I/O to at least get a better idea of what’s going on, but something tells us we could be in for a treat.
What do you think about a standalone Google VR headset? Let us know your thoughts in the comments below.
Source: Wall Street Journal via engadget
The post Standalone Google VR headset is also being worked on behind the scenes appeared first on AndroidSPIN.
GTA: Liberty City Stories is out now, 40% off for a limited time
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For Rockstar Games, the mobile gaming revolution has been a great time to dig out all its last-gen games (or in some cases last-last-gen) and repackage them for mobile platforms – and let’s be honest: it’s a win-win situation. The next game on Rockstar’s list of revivals is GTA: Liberty City Stories, which was originally released in 2005 on the Playstation Portable. For those aren’t experiencing a nostalgia trip, GTA: Liberty City Stories sees you take control of Toni Cipriani, who once worked for the Leone family. Liberty City is now in a bad state, with warring families, organized crime, and corrupt politicians all making it difficult for Cipriani in his quest to get the Leone family control of the city.
Rockstar says that it has streamlined the whole mobile experience with shortened missions, better controls and updated graphics, much like Rockstar’s previous efforts when reviving its older games. For a limited time, starting from today’s launch, GTA: Liberty City Stories is going to be 40% off, making it $3.99 USD during this discounted period – not a bad deal for a feature length game, and probably well worth the nostalgia. If you’re hankering for a trip back to Liberty City, we’ve got the Play Store link for you down below:
http://playboard.me/widgets/pb-app-box/1/pb_load_app_box.jsWhat do you think about GTA: Liberty City Stories? Let us know your thoughts in the comments below.
Source: Droid-life
The post GTA: Liberty City Stories is out now, 40% off for a limited time appeared first on AndroidSPIN.
Facebook is testing SMS, multiple accounts in Messenger
Facebook has slowly beefed up its Messenger offering over the past year, with not only the ability to send payments and hail an Uber ride, but also the addition of an AI-inspired personal assistant (or at least the promise of). Now it looks like Messenger will have a couple of other features added in the near future: the integration of SMS plus support for multiple accounts. It was first seen on Android Police but we’ve since received confirmation from Facebook that the company is indeed testing these new features.
“At Messenger we are always trying to create new ways for people to communicate seamlessly with everyone,” said a Facebook spokesperson. “Right now, we’re testing the ability for people to easily bring all their conversations — from SMS and Messenger — to one place. It’s a really simple way to get, see and respond to all your SMS messages in just one app. By choosing to access your SMS messages in Messenger, they’re right alongside all the other enhanced features that Messenger offers.”
We should note here that SMS was actually a part of Facebook Messenger before, but it was removed a few years ago due to low adoption. But perhaps with the advent of messaging apps like WhatsApp and Google’s Hangouts, Facebook had a change of heart. From the Android Police screenshots, it looks like the SMS messages will be colored differently — purple instead of blue — and that it’s an optional feature that can be enabled or disabled in settings.
Screenshot credit: Android Police
As for multiple accounts on Messenger, Facebook had this to say: “Millions of people share phones with their family and friends. Until now, there hasn’t been an easy way for people to access their individual Messenger accounts from shared devices. To address this, we’ve launched a feature on Android to enable multiple people to log in and use Messenger from a single phone.”
We’re not quite sure why family and friends would want to share Messenger accounts on a single phone, but we can see this feature being more useful in a tablet, where it’s more likely to be a shared household device. It could also be useful if you have both a personal and a professional account. From the looks of it, you can add accounts to the Messenger app in settings and be able to switch between them as you wish. There’s no telling when these features will arrive for all Android phones, but we wouldn’t be surprised if they appeared on your device in the near future.
Source: Android Police
AIVAnet 