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Full Discussion: Lseek implementation
Top Forums UNIX for Dummies Questions & Answers Lseek implementation Post 302554793 by Humudituu on Tuesday 13th of September 2011 05:37:37 AM
Old 09-13-2011
Question Lseek implementation
Hi everybody,

i've been googling for ages now and gotten kinda desperate... The question, however, might be rather trivial for the experts: What is it exactly, i.e. physically, the POSIX function (for a file) "lseek" does? Does it trigger some kind of synchronization on disk? Is it just for the file system?

Rationale:
I'm am running some benchmarks to get an idea, how our system (ext4@Debian5) works. I'm having 100 threads reading or writing randomly small requests on disk (POSIX read/write with DIRECT_IO) -> read,lseek,read,lseek,... or write,lseek,write,lseek,... . The mean lseek response time while reading is marginally small, however, the mean lseek response time while writing is appr. as high as the mean response time of a write itself (several ms), and I don't know why...

Any help is appreciated.
 

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LEARN ABOUT DEBIAN

gpe-question

GPE-QUESTION(1) 						   gpe-question 						   GPE-QUESTION(1)

NAME

       gpe-question - GPE interface for asking questions from shell scripts.

SYNOPSIS

       gpe-question [---icon] name {--question "Question text"} {--buttons icon1:text1} [icon2:text2 ...]

DESCRIPTION

       This manual page was written for the Debian(TM) distribution because the original program does not have a manual page.

       gpe-question provides dialogues to raise a question within the GPE Palmtop Environment with cancel and ok buttons.

OPTIONS

       --question STRING
	  The question to ask the user via the dialogue.

       --buttons type:label
	  The type and label of the button(s) to be shown. Repeat for additional buttons.

EXAMPLES

       gpe-question "test" --question "Do you want to check first?"  --buttons YES:yes NO:no

AUTHOR

       This manual page was written by Neil Williams <codehelp@debian.org> for the Debian(TM) system (but may be used by others). Permission is
       granted to copy, distribute and/or modify this document under the terms of the GNU General Public License, Version 2 any later version
       published by the Free Software Foundation.

       On Debian systems, the complete text of the GNU General Public License can be found in /usr/share/common-licenses/GPL.

AUTHOR

       Moray Allen
	  Author.

COPYRIGHT

       Copyright (C) 2007 Neil Williams

Debian 1							 January 16, 2007						   GPE-QUESTION(1)
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