描述

IC693CMM321

許多人都把實(shí)時(shí)性理解為速度快。那么，速度快到什么程度才算是達(dá)到實(shí)時(shí)性呢？其實(shí)，所謂實(shí)時(shí)性，其核心含義在于確定性，而不是單純的速度快。也就是說，RTOS所要求的是在規(guī)定的時(shí)間內(nèi)做完應(yīng)該做的事情，并且操作系統(tǒng)的行為（執(zhí)行線索）是確定的，這是寫出高可靠性程序的基礎(chǔ)。如果完成同樣的動(dòng)作，有的時(shí)候快，有的時(shí)候慢，且執(zhí)行線索千差萬別，程序員無法把握，可靠性就無從保證。
嵌入式系統(tǒng)為什么對(duì)實(shí)時(shí)性要求那么高呢？因?yàn)榍度胧较到y(tǒng)主要是對(duì)儀器設(shè)備的動(dòng)作進(jìn)行監(jiān)測(cè)控制的，而一般的桌面操作系統(tǒng)基本上是根據(jù)人在鍵盤和鼠標(biāo)發(fā)出的命令進(jìn)行工作。相對(duì)而言，儀器設(shè)備的動(dòng)作具有嚴(yán)格的、機(jī)械的時(shí)序要求，而人的動(dòng)作和反應(yīng)在時(shí)序上并不那么嚴(yán)格。比如，用于控制火箭發(fā)動(dòng)機(jī)的嵌入式系統(tǒng)，它所發(fā)出的指令不僅要速度快，而且多個(gè)發(fā)動(dòng)機(jī)之間的時(shí)序要求非常嚴(yán)格，否則就會(huì)差之毫厘、謬之千里。在這樣的應(yīng)用環(huán)境中，非實(shí)時(shí)的普通操作系統(tǒng)無論如何是無法適應(yīng)的。
如果我們所開發(fā)的設(shè)備并不是像航空航天器那樣生命攸關(guān)或者生產(chǎn)控制那樣的關(guān)鍵任務(wù)系統(tǒng)，而是像消費(fèi)電子類那樣，即使出現(xiàn)錯(cuò)誤也不會(huì)造成災(zāi)難性后果的設(shè)備，那么實(shí)時(shí)性（嚴(yán)格地講是確定性）是否還具有現(xiàn)實(shí)意義呢？答案是肯定的！設(shè)備的高可靠性可以有效地降低維護(hù)成本；軟件運(yùn)行效率高也會(huì)降低對(duì)CPU的要求，從而降低硬件成本。對(duì)于消費(fèi)電子產(chǎn)品這類價(jià)格十分敏感的產(chǎn)品，實(shí)時(shí)性、可靠性仍然是非常值得重視的問題。

產(chǎn)品承諾：
保?證?全新原裝進(jìn)口,
保?證?安全準(zhǔn)時(shí)發(fā)貨，
保?證售后服務(wù)質(zhì)量，
優(yōu)勢(shì)價(jià)格，大量現(xiàn)貨。

主營(yíng)DCS系統(tǒng)配件
機(jī)器人系統(tǒng)配件
大型伺服系統(tǒng)配件
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