Mobile developers need to face up to multicore challenge

Writing applications for devices like tablets and smartphones could become more challenging as CPUs and hardware accelerators are added to mobile chips, experts agreed at a processor conference.

Chip makers are adding CPUs and specialised hardware accelerators to mobile chips as an energy efficient way to boost application performance on tablets and smartphones. Most mobile devices today come with one CPU core on a chip, but tablets and smartphones with dual- and triple-core chips could hit shelves as early as next year.

That means that applications must be rewritten to take advantage of the new hardware, said Linley Gwennap, principal analyst at Linley Group, during the Linley Tech Processor conference. A lot of work would be needed in software to extract better performance out of multicore chips, which could be a challenge, Gwennap said.

"What we're seeing on the phone side is applications having to change to use the second CPU," Gwennap said. "It's going to take some time before the software is ready for that," Gwennap said.

But it's a challenge that programmers are likely to meet. Smartphone and tablet shipments are growing fast, and developers are churning out new programs designed to get an early foothold in these exciting markets.

New smartphones such Apple's iPhone 4, Motorola's Droid X and HTC's Evo 4G carry the fastest processors ever, running at clock speeds of 1GHz. The tablet market is ruled by Apple's iPad, but it will heat up as challengers such as Samsung's Galaxy Tab and Toshiba's Folio 100 begin shipping. Research in Motion on Monday announced its new tablet, called the PlayBook.

Mobile devices are undergoing a transition from voice and SMS to more data services, and applications remain connected for longer, said Kannan Parthasarathy, an engineer at Byte Mobile. "It started off with web browsing, now people are watching video," she said.

There are also social media applications that remain connected for longer, which calls for more processing power and improved network connectivity. To save battery life, developers need to understand mobile applications, services and connectivity, and break down tasks over cores and threads accordingly.

Mobile operating systems like Google's Android are partly ready for dual CPUs at the OS level, which could initially reduce the strain on programmers, Gwennap said. But as mobile chips carry more cores, there will be more complexity in implementing applications over multiple cores and threads.

Qualcomm and Nvidia have announced dual CPU chips based on ARM designs for smartphones and tablets. But Marvell has already released a chip with three processing cores, and the number of cores on mobile chips could increase over time as devices demand more performance while saving power.

"As you go beyond four cores... you really have to start stripping down the OS," Gwennap said.