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Full Discussion: Which cut command is more efficient?
Top Forums UNIX for Advanced & Expert Users Which cut command is more efficient? Post 302508570 by Corona688 on Monday 28th of March 2011 01:08:51 PM
Old 03-28-2011
Quote:
Originally Posted by methyl
My stats do not show waste of CPU power. They show a CPU power saving by using "cat" because "cut" is less efficient at reading files.
So reading the file, writing it to a pipe, and reading from the pipe, utilizing two separate CPU's simultaneously is more efficient than reading it once and using it once? If your CPU benchmarks show that this uses less CPU, frankly, they're wrong. Less total real time maybe, but nothing in that reduces the amount of CPU cut uses -- adding more commands can only add more CPU utilization.

The only performance benefit I can see is the pipe effectively acts as a read-ahead buffer, albeit a highly expensive one. With the power expended for that 1% performance improvement, how much more actual work could have been done instead by running two instances of cut on different data sets?

---------- Post updated at 11:08 AM ---------- Previous update was at 10:58 AM ----------

Quote:
Originally Posted by shamrock
What makes you arrive at the fact that..."cut" is less efficient at reading files than cat.
cut has to read line by line. cat can just read and write huge blocks.
Last edited by Corona688; 03-28-2011 at 02:14 PM..
 

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LEARN ABOUT OPENDARWIN

rest

rest(3alleg4)							  Allegro manual						     rest(3alleg4)

NAME

       rest - Waits a specified number of milliseconds or yields CPU. Allegro game programming library.

SYNOPSIS

       #include <allegro.h>

       void rest(unsigned int time);

DESCRIPTION

       This function waits for the specified number of milliseconds.

       Passing	0  as  parameter will not wait, but just yield. This can be useful in order to "play nice" with other processes. Other values will
       cause CPU time to be dropped on most platforms. This will look better to users, and also does things like saving battery power  and  making
       fans less noisy.

       Note  that  calling this inside your active game loop is a bad idea, as you never know when the OS will give you the CPU back, so you could
       end up missing the vertical retrace and skipping frames. On the other hand, on multitasking operating systems it is good form  to  give	up
       the CPU for a while if you will not be using it.

SEE ALSO

       install_timer(3alleg4), rest_callback(3alleg4), vsync(3alleg4), d_yield_proc(3alleg4)

Allegro 							   version 4.4.2						     rest(3alleg4)
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