Making things run faster Post: 302248460

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Top Forums UNIX for Advanced & Expert Users Making things run faster Post 302248460 by shamrock on Friday 17th of October 2008 05:33:21 PM

10-17-2008

Registered User

Quote:

Originally Posted by Legend986

Added to that, I have a small question (not so sure if its silly though but can't seem to understand it completely)...

If I have four datasets like in the problem above and all I have to do is grep some text out of it, does it really make a difference doing the jobs parallely on all the datasets or doing them in a sequential order? In fact, to be more precise, the argument goes something like this:

Four datasets are stored on the disk. The CPU has to fetch some data everytime for the four processes to process them and write back to the disk. Now, if it has to provide data to all the four processes, then shouldn't the head keep moving around to provide the data as opposed to just one process where it just keeps reading the data (provided there is no fragmentation). As I said, I'm sorry if my question seems silly but just want to clear some basic concepts.

And that is the reason for caching data and striping it over multiple disks in order to reduce disk arm contention. This way reads/writes are done in parallel and with caching in play most reads/write are logical instead of physical. As you have terabytes of data I am assuming that all of it isn't on a single drive like a JBOD of some sort and that it is on a high end storage array with significant intelligence and caching built into it while being striped for performace and mirrored for availability.

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moose::cookbook::basics::immutable

Moose::Cookbook::Basics::Immutable(3)			User Contributed Perl Documentation		     Moose::Cookbook::Basics::Immutable(3)

NAME

       Moose::Cookbook::Basics::Immutable - Making Moose fast by making your class immutable

VERSION

       version 2.0604

SYNOPSIS

	 package Point;
	 use Moose;

	 has 'x' => ( isa => 'Int', is => 'ro' );
	 has 'y' => ( isa => 'Int', is => 'rw' );

	 __PACKAGE__->meta->make_immutable;

DESCRIPTION

       The Moose metaclass API provides a "make_immutable()" method. Calling this method does two things to your class. First, it makes it faster.
       In particular, object construction and destruction are effectively "inlined" in your class, and no longer invoke the meta API.

       Second, you can no longer make changes via the metaclass API, such as adding attributes. In practice, this won't be a problem, as you
       rarely need to do this after first loading the class.

CONCLUSION

       We strongly recommend you make your classes immutable. It makes your code much faster, with a small compile-time cost. This will be
       especially noticeable when creating many objects.

AUTHOR

       Moose is maintained by the Moose Cabal, along with the help of many contributors. See "CABAL" in Moose and "CONTRIBUTORS" in Moose for
       details.

COPYRIGHT AND LICENSE

       This software is copyright (c) 2012 by Infinity Interactive, Inc..

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

perl v5.16.2							    2012-09-19				     Moose::Cookbook::Basics::Immutable(3)