Samsung officially unveiled the much awaited new flagship the Galaxy S4 on 14th March. That event confirmed the existence of a octa core chipset on the device. The chipset is Samsung‘s home grown Exynos 5 Octa SoC. It is given that this would be faster than the Exynos quad chipset. Lets take a look under the hood.
The chip actually has eight cores,that bit is true. It has 8 different cores in the Soc. But not all the cores are equal.
The most challenging part in designing a chip is get a optimal balance between performance and power consumption. Most chipsets activate all the cores during a high intensity task but lower the clock speed and disable few cores during idle or light use. The Exynos 5 octa chipset attempts to solve this problem by using a CPU configuration called “big.LITTLE”.
This configuration pairs two cores: one low powered and one high powered i.e one smaller more power efficient core and one larger more powerful core. These two cores support the same instruction sets and can execute all of the same code, so speed and power consumption are the main differences between them. So, light tasks light web browsing, scrolling etc use the low powered core while computationally intensive tasks like gaming use the more powerful chipset. In the S4, the low powered core is the Cortex-A7 running at 1.6GHz and the more powerful core is the Cortex-A15 running at 1.2GHz.
The core switching is controlled by a firmware layer that sits in between the software and the chip itself. Any OS that has power management feature can take advantage of the Big-LITTLE configuration.
Different versions of this idea have existed in shipping products for some time now — the most prominent example is probably Nvidia’s Tegra chips, which include a single “companion” or “shadow” core that kicks in for light use so that the more power-hungry main CPU cores can switch off.Since the Exynos 5 Octa is the first big.LITTLE chip to ship, no real world benchmark tests have been done to compare.
Upto the last gen Exynos processors, Samsung depended upon the Mali-400 GPU to handle the graphical tasks. For the S4, Sammy has decided to dump the aging GPU in favor of the PowerVR SGX 544MP3. Its a triple core GPU. The 544MP3 is in fact very similar to the triple core 543MP3 found in the Apple A6.The performance would be more or less similar but we also have to take into account the higher res display of the S4.
The battery life under various workloads remains to be seen–as companies continue trying to push the performance envelope without destroying their devices’ battery lives, chips like the Octa are only going to become more common.