From: "Yury A. Zaitsev" <yurick AT oblik DOT dp DOT ua>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: __djgpp_map_physical_memory - some questions
Date: Wed, 13 Jun 2001 19:56:29 +0300
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Mon, 11 Jun 2001, DJ Delorie <dj AT delorie DOT com> wrote:

>> Is DOS _really_ so slow?
DD> No, but consider that Unix keeps track of the time *as* a time_t, so
DD> time() merely reads a number from memory and returns it - a few CPU
DD> cycles at best.  DOS, however, uses the hardware realtime clock, so it
DD> must convert month/day/year/hour/minute/second/timezone to a time_t
DD> each time you need to know what time it is.  The conversion is slow.
	Well, but why time() simply not caches this values (month/day/year/
hour/minute/second/timezone) (such as Linux kernel does)? If time() will
remember old values of year, month, day and timezone, it will works many 
times faster (it'll needs only to add sec+60*(min+60*hour)).
   I've tested mktime()'s speed just now and yes, you are right.
mktime() is a bottle-neck of the time(). It takes about 70-80% of the 
time()'s time :)