linux-ext4 - Re: What represent 646345728 bytes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20027776.19701265044015458.JavaMail.www@wsfrf1112>
Date:	Mon,  1 Feb 2010 18:06:55 +0100 (CET)
From:	<paul.chavent@...c.net>
To:	linux-ext4@...r.kernel.org
Subject: Re: What represent 646345728 bytes

Thank you Eric for your reply.

My problem with preallocation is that i don't know the size of my final tar archive. So i would prefer to don't make any supposition.

Yes, i write a stream of 640x480x1 pnm images (307215 bytes each) to a single tar file.
So lets say that each write is 307712 (divisible by 512 bytes for tar).

Here is a test bench program that reproduce the behaviour of the real app.

The program log some write overhead at 645579776bytes and other at 645887488bytes, so not exactly the same thing as in the real app.

You will be able to tell me if my test bench is correct (metric, compilation options, etc.).

The system on which i run the test bench has no other workload, no other disk access.

Please find the attached files : 
- test bench source 
- the dumpe2fs log

Tonight, i will try with the "-O ^uninit_bg at mkfs time".

Thanks.

Paul.

View attachment "dumpe2fs.txt" of type "text/plain" (1695 bytes)

Download attachment "main.c" of type "application/octet-stream" (3991 bytes)