ARM 日前推出據(jù)稱是迄今旗下產(chǎn)品中能源效率最高的應(yīng)用處理器 ARM Cortex-A7 MPCore ，以及全新的高彈性 big.LITTLE 處理器技術(shù)。該公司表示新核心是除了頂級 Cortex-A15 以外，該公司的異質(zhì)功率驅(qū)動多核心產(chǎn)品策略的一部份。 A7是一款雙指令執(zhí)行、八階管線的核心，已針對低功耗進行最佳化，但卻可支持與A15相同的虛擬化擴展尋址功能。藉由推出新的 A7 ， ARM 希望合作伙伴能落實其‘little dog, big dog’策略，依照不同的功率需求，為應(yīng)用選擇不同核心。 A7處理器可以有單核或雙核版本，主要瞄準的是對價格敏市場中的入門級智能手機應(yīng)用。 ARM CEO Warren East 在英國發(fā)布 A7 時表示，他預計市面上將出現(xiàn)多核心方案，在2013年，智能手機或許可開始采用雙核心A15加上雙核心A7的解決方案。 所謂的‘big.LITTLE’策略，意指在需要較低性能時可用一個或多個A7核心來‘永遠執(zhí)行’(always-on)任務(wù)，以最大限度地延長電池壽命，而當手機需要執(zhí)行更高性能的任務(wù)時，便可轉(zhuǎn)移到A15核心。藉由ARM的系統(tǒng)IP，如AMBA 4 ACE一致性擴展，這種動態(tài)的核心選擇能讓執(zhí)行于處理器上的應(yīng)用軟件和中介程序更加透明。該公司表示，在A7和A15處理器核心之間的任務(wù)轉(zhuǎn)移均由相同的系統(tǒng)觸發(fā)，并驅(qū)動動態(tài)電壓和頻率調(diào)節(jié)，這在先進的系統(tǒng)芯片中幾乎已成為必要功能。

基于雙核心A7和A15處理器的系統(tǒng)架構(gòu)示意圖。Vg3esmc

采用28nm的A7體積不到45nm制程之Cortex-A8的五分之一，但卻能提供更高性能和提升功率效率。一個采用28nm的雙核心A7處理器與90nm的雙核心A9處理器相比，大約可節(jié)省70%的電力。換句話說，它的功耗大約只有A9的三分之一。 目前有2~3家主要伙伴已經(jīng)在開發(fā)基于A7的產(chǎn)品，East說，但他拒絕透露是哪些公司。ARM正積極拓展A7核心的授權(quán)。包括博通(Broadcom)、飛思卡爾(Freescale)、海思(HiSilicon)、三星(Samsung)、ST-Ericsson和德州儀器(TI)都名列支持廠商，另外還包括系統(tǒng)和軟件公司如仁寶(Compal)、LG Electronics、Linaro、OK Labs、QNX、Redbend和Sprint等。 “我們?nèi)ツ晖瞥鯝15，大幅推升了處理器性能。但對ARM來說，功效也是最關(guān)鍵的重點。A7是當最最具功效的一款核心?！币拦男枨髞磉x擇處理資源這個概念之前便已經(jīng)在某些產(chǎn)品中出現(xiàn)過了，例如在繪圖處理器領(lǐng)域，該公司的處理器部門副總經(jīng)理Tom Cronk說，但這個構(gòu)想并沒有用在通用處理器核心上。 Cortex-A7處理器的面積小于0.5mm2，采用28-nm制程，在1.2GHz時脈頻率下，以單核或多核心配置均可提供顯著性能。預估2013~2014年，Cortex-A7將用于100美元以下的智能手機中，但卻能提供與今天500美元以上智能手機相同水準的處理性能，ARM表示。 盡管A7目前瞄準智能手機市場，但East認為未來該核心也將擴展到其它應(yīng)用領(lǐng)域。East預計，未來新產(chǎn)品將部署到包括消費電子產(chǎn)品和其它亟需更高功效的應(yīng)用市場中。 Cortex-A7預計2012上半年投片，SoC產(chǎn)品預計2013年問世，East說。 編譯： Joy Teng 本文授權(quán)編譯自EE Times，版權(quán)所有，謝絕轉(zhuǎn)載 參考英文原文： ARM reveals 'little dog' A7 processor，by Peter Clarke

相關(guān)閱讀：
• 多方加入Cortex-M4 MCU混戰(zhàn)，通用內(nèi)核時代是否已到來？
• Altera發(fā)布ARM A9 SoC FPGA，明年下半年出工程樣片
• 威盛起訴蘋果侵犯其處理器設(shè)計專利Vg3esmc

{pagination} ARM reveals 'little dog' A7 processor Peter Clarke LONDON – Processor IP licensor ARM Holdings plc has revealed a power efficient Cortex-A7 processor core that it says is intended to be used alongside its top-of-the-range Cortex-A15 as part of a heterogeneous power-driven multicore strategy. The A7 is a dual-issue, eight-stage pipeline core that has been heavily optimized for power efficiency, but supports the same virtualization and extended addressing as the A15. As a result ARM (Cambridge, England) expects partners to implement a "little dog, big dog" strategy so that cores are selected to run applications based on power efficiency needs. Alternatively, the A7 processor can be used in single- or dual-core instantiations stand-alone to power an entry-level smartphone for price sensitive markets, ARM said. Warren East, speaking at the U.K. launch of the A7, said that he expected multicore chips, which could be dual-core A15 plus dual-core A7, to be in the market and powering smartphones in 2013. The "big-little" strategy allows low-performance basic and always-on tasks to be run on one or more A7 cores, to maximize battery life, while tasks requiring greater performance would migrate to the A15 cores. This dynamic core selection can be made transparent to the application software and middleware running on the processors, supported by advanced ARM system IP, such as AMBA 4 ACE Coherency Extensions. The movement of tasks between paired A7 and A15 cores is triggered by the same system that drives the dynamic voltage and frequency scaling that has become traditional in leading-edge system chips, the company said. A coherent "big-little" system-chip based on internal dual-core A7 and A15 processors In a 28-nm process the A7 is less than one fifth the size of the Cortex-A8 in a 45-nm process, while providing greater performance and much greater power efficiency, the company said. A dual-core A7 processor in 28-nm would produce about a 70 percent power saving compared with a dual-core A9 processor implemented in 40-nm. In other words it will consume about one-third the power. ARM had two or three lead partners on the development of the A7 and the associated big-little strategy, East said, but he declined to name them individually. ARM now has a wave of semiconductor licensees eager to use the A7 core. Broadcom, Freescale, HiSilicon, Samsung, ST-Ericsson and Texas Instruments are listed as supporting the technology along with system and software companies Compal, LG Electronics Linaro, OK Labs, QNX, Redbend and Sprint. "We took the A15 to market last year because we needed to push the performance envelope. But power efficiency is the most important thing for ARM. The A7 is the most efficient core yet," said East. Tom Cronk, deputy general manager of the processor division at ARM said that power efficiency driven selection of resources has been used before, for example in the area of graphics but not for general purpose processor cores. The Cortex-A7 processor occupies less than 0.5 square millimeters, using a 28-nm process technology, and provides useful performance at about 1.2-GHz clock frequency in both single and multicore configurations. Used as a stand-alone processor, the Cortex-A7 will deliver sub-$100 entry level smartphones in the 2013-2014 timeframe with an equivalent level of processing performance to today’s $500 high-end smartphones, ARM said. While A7 is aimed initially at smartphones East said he was sure the big-little strategy was applicable in other areas. East said he expected power-driven resource allocation would subsequently be deployed in consumer electronics and any area where complex processing also met a need for power efficiency. Tape-outs including the Cortex-A7 are expected in the first half of 2012 with SoCs and products based on them to follow in 2013, East said.