Re: [Pfspd-users@sf.net] File fragmentation

[Bram R. <bra...@ph...>]

Hi Harold, others,

After some more testing ... I found on win32/cygwin:
An existing large file remained large after p_write_header and was only 
truncated when closing the file.
Hence, an existing fragmented file remained fragmented.

This is resolved by a different CreateFile flag in cpfspd_fio.c.
Now, the file is created as if it did not exist, hence also new disk space 
is allocated with p_write_header.

Solution is in CVS repository.

Regards, Bram.

--
A.K. (Bram) Riemens
Principal Scientist, DSP group, Philips Research
Office: WO-p-94, Postbox WO02
High Tech Campus 36 (WO), 5656 AE Eindhoven, The Netherlands
Tel: +31 40 27 43833, Fax: +31 40 27 44675
E-mail: bra...@ph...








Harold Schmeitz 
Sent by:
pfs...@li...
22-05-2006 09:04

To
pfs...@li...
cc

Subject
Re: [Pfs...@sf...] File fragmentation
Classification








Hello, 

Thanks to Bram's rigorous testing, we uncovered a problem with the win32 
file I/O. 

In overlapped (asynchronous) mode, reserving the file space does not 
complete immediately, 
but it appears that some data (zeros ?) is written to disk. On a local 
file system, this takes some time, but works ok. 
However,on a network share (e.g. writing remotely to a streamer pc), there 
is a timeout after 2-3 GB, and the application crashes. 

Workaround is to create a file using regular I/O, reserve disk space, 
close it, then open again in overlapped mode. 
The disk space allocation is moved to p_fio_allocate( ). 

Please note that this only affects you if you are using the development 
version of cpfspd (sf.net), so update your cvs sandbox. 

Regards, 
Harold
___________________________________
Ing. H.A.W. Schmeitz
Video Processing Systems, Philips Research Laboratories

High Tech Campus 36, 5656 AE Eindhoven, The Netherlands
Tel. +31 (0)40 27 46489
har...@ph...