Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.glorb.com!news-out.readnews.com!transit3.readnews.com!panix!not-for-mail From: Grant Edwards Newsgroups: comp.os.linux.advocacy,comp.os.linux.embedded,uk.comp.os.linux Subject: Re: Why does Linux need memory management units and cache? Date: Sun, 20 May 2012 14:42:20 +0000 (UTC) Organization: PANIX Public Access Internet and UNIX, NYC Lines: 38 Message-ID: References: <2RQtr.477893$y11.316125@fx21.am4> NNTP-Posting-Host: c-24-118-110-103.hsd1.mn.comcast.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: reader1.panix.com 1337524940 6978 24.118.110.103 (20 May 2012 14:42:20 GMT) X-Complaints-To: abuse@panix.com NNTP-Posting-Date: Sun, 20 May 2012 14:42:20 +0000 (UTC) User-Agent: slrn/0.9.9p1 (Linux) Xref: csiph.com comp.os.linux.advocacy:108174 comp.os.linux.embedded:271 On 2012-05-19, 7 wrote: > Niklas Holsti wrote: > >> On 12-05-19 15:40 , 7 wrote: >>> Why does Linux need memory management units and cache? >>> ------------------------------------------------------ >>> >>> Excuse us, this is bothering me much. >>> >>> Why does Linux need memory management units >> >> To implement virtual address spaces for processes. > > Virtual address space in a nut shell means program counter relative > operation. No, that's not what virtual address space means. >> Linux doesn't need cache, logically. But Linux systems usually need >> lots of memory, more than can be provided on chip, and access to >> off-chip memories is usually so slow that a cache makes the system >> much faster. > > So a cache could be implemented in software. Not really, no. > And if done properly with a fast program, it should run faster and > better than hardware Nope. > which would use up a lot more software in setting up and managing a > cache. -- Grant